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Three reports are presented on computer graphics testbed to simulate and test vision systems for space applications.

Three reports are presented on computer graphics testbed to simulate and test vision systems for space applications.

Three reports are presented on computer graphics testbed to simulate and test vision systems for space applications.

Three reports are presented on computer graphics testbed to simulate and test vision systems for space applications.

The Executive Information Services (EIS) system, developed as a computer-based, time-sharing tool for making and implementing management decisions, and including computer graphics capabilities, was described. The following resources are available through the EIS languages: centralized corporate/gov't data base, customized and working data bases, report writing, general computational capability, specialized routines, modeling/programming capability, and graphics. Nearly all EIS graphs can be created by a single, on-line instruction. A large number of options are available, such as selection of graphic form, line control, shading, placement on the page, multiple images on a page, control of scaling and labeling, plotting of cum data sets, optical grid lines, and stack charts. The following are examples of areas in which the EIS system may be used: research, estimating services, planning, budgeting, and performance measurement, national computer hook-up negotiations.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

The Chromium Projects Home Chromium ChromiumOS Quick links Report bugs Discuss Other sites Chromium Blog Google Chrome Extensions Except as otherwise  noted , the content of this page is licensed under a  Creative Commons Attribution 2.5 license , and examples are licensed under the  BSD License . Privacy Edit this page For Developers  >  How-Tos  > Debugging Chromium on Windows First see  get the code  for checkout and build instructions. Getting started You can use Visual Studio's built-in debugger or  WinDBG  to debug Chromium. You don't need to use the IDE to build in order to use the debugger: autoninja is used to build Chromium and most developers invoke it from a command prompt, and then open the IDE for debugging as necessary. To start debugging an already-built executable with Visual Studio just launch Visual Studio (2019 or higher) and select File-> Open-> Project/Solution (Ctrl+Shift+O) and select the executable of interest. This will create a solution with that executable as the 'project'. You can then launch the debugger with F5 or F11 or from the Debug menu. If you right-click on the executable in Solution Explorer and select properties then you can edit things such as the executable path, command-line arguments, and working directory. You can add additional executables to the solution by using File-> Add-> Existing Project and selecting another already-built executable. You can select which one to debug by right-clicking on one of them in Solution Explorer and selecting Set as Startup Project. When your solution file is customized to your taste you can save it to a directory such as out\solutions. Saving it there helps ensure that relative paths to source files, printed from build commands, will correctly identify the source files. The Tools menu can be used to add commands to do things like invoke autoninja to build Chrome, compile the selected source file, or other things. Visual Studio 2017 is not recommended for debugging of Chromium - use a newer version for best performance and stability. symbol_level=2  is the default on Windows and gives full debugging information with types, locals, globals, function names, and source/line information.  symbol_level=1  creates smaller PDBs with just function names, and source/line information - source-level debugging is still supported (new from June 2019), but local variables and type information are missing.  symbol_level=0  gives extremely limited debugging abilities, mostly just viewing call stacks when Chromium crashes. Browsing source code If you use a solution file generated by gn ( gn gen --ide=vs ) then Intellisense may help you navigate the code. If this doesn't work or if you use a solution created as above then you may want to install  VsChromium  to help navigate the code, as well as using  https://source.chromium.org . Profiles It's a good idea to use a different Chrome profile for your debugging. If you are debugging Google Chrome branded builds, or use a Chromium build as your primary browser, the profiles can collide so you can't run both at once, and your stable browser might see profile versions from the future (Google Chrome and Chromium use different profile directories by default so won't collide). Use the command-line option: --user-data-dir =C:\tmp\my_debug_profile (replace the path as necessary) Using the IDE, go to the  Debugging  tab of the properties of the chrome project, and set the  Command Arguments. Chrome debug log Enable Chrome debug logging to a file by passing  --enable-logging --v=1  command-line flags at startup. Debug builds place the  chrome_debug.log  file in the  out\Debug  directory. Release builds place the file in the top level of the user data Chromium app directory, which is OS-version-dependent. For more information, see  logging  and  user data directory  details. Symbol server If you are debugging official Google Chrome release builds, use the symbol server: https://chromium-browser-symsrv.commondatastorage.googleapis.com In Visual Studio, this goes in  Tools > Options  under  Debugging > Symbols . You should set up a local cache in a empty directory on your computer. In windbg you can add this to your symbol server search path with the command below, where C:\symbols is a local cache directory: .sympath+ SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Alternately, You can set the _NT_SYMBOL_PATH environment variable to include both the Microsoft and Google symbol servers - VS, windbg, and other tools should both respect this environment variable: _NT_SYMBOL_PATH =SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols ;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com Note that symbol servers will let the debuggers download both the PE files (DLLs and EXEs) and the PDB files. Chrome often loads third party libraries and partial symbols for some of these are also public. For example: AMD : https://download.amd.com/dir/bin Nvidia : https://driver-symbols.nvidia.com/ Intel : https://software.intel.com/sites/downloads/symbols/ For example, for completeness, the following symbol server environment variable will resolve all of the above sources - but this is more than is normally needed: _NT_SYMBOL_PATH=SRV\*C:\symbols\*https://msdl.microsoft.com/download/symbols;SRV\*C:\symbols\*https://chromium-browser-symsrv.commondatastorage.googleapis.com;SRV\*C:\symbols\*https://download.amd.com/dir/bin;SRV\*C:\symbols\*https://driver-symbols.nvidia.com/;SRV\*C:\symbols\*https://software.intel.com/sites/downloads/symbols/ Source indexing You should set up source indexing in your debugger ( .srcfix  in windbg, Tools-> Options-> Debugging-> General->  Enable source server support  in Visual Studio) so that the correct source files will automatically be downloaded based on information in the downloaded symbols. Additionally, you must have  python  in your  path  in order for the  command that fetches source files  to succeed; launching the debugger from the same environment as where you build Chromium is an easy way to ensure it's present. This is highly recommended when debugging released Google Chrome builds or looking at crash dumps. Having the correct version of the source files automatically show up saves significant time so you should definitely set this. Multi-process issues Chromium can be challenging to debug because of its  multi-process architecture . When you select  Run  in the debugger, only the main browser process will be debugged. The code that actually renders web pages (the Renderer) and the plugins will be in separate processes that's not (yet!) being debugged. The  ProcessExplorer  tool has a process tree view where you can see how these processes are related. You can also get the process IDs associated with each tab from the Chrome Task Manager (right-click on an empty area of the window title bar to open). Automatically attach to child processes There are two Visual Studio extensions that enable the debugger to automatically attach to all Chrome processes, so you can debug all of Chrome at once. Microsoft's  Child Process Debugging Power Tool  is a standalone extension for this, and  VsChromium  is another option that bundles many other additional features. In addition to installing one of these extensions, you  must  run Visual Studio as Administrator, or it will silently fail to attach to some of Chrome's child processes. Single-process mode One way to debug issues is to run Chromium in single-process mode. This will allow you to see the entire state of the program without extra work (although it will still have many threads). To use single-process mode, add the command-line flag --single-process This approach isn't perfect because some problems won't manifest themselves in this mode and some features don't work and worker threads are still spawned into new processes. Manually attaching to a child process You can attach to the running child processes with the debugger. Select  Tools > Attach to Process  and click the  chrome.exe  process you want to attach to. Before attaching, make sure you have selected only Native code when attaching to the process This is done by clicking Select... in the Attach to Process window and only checking Native. If you forget this, it may attempt to attach in "WebKit" mode to debug JavaScript, and you'll get an error message "An operation is not legal in the current state." You can now debug the two processes as if they were one. When you are debugging multiple processes, open the  Debug > Windows > Processes  window to switch between them. Sometimes you are debugging something that only happens on startup, and want to see the child process as soon as it starts. Use: --renderer-startup-dialog --no-sandbox You have to disable the sandbox or the dialog box will be prohibited from showing. When the dialog appears, visit Tools > Attach to Process and attach to the process showing the Renderer startup dialog. Now you're debugging in the renderer and can continue execution by pressing OK in the dialog. Startup dialogs also exist for other child process types:  --gpu-startup-dialog ,  --ppapi-startup-dialog ,  --utility-startup-dialog ,  --plugin-startup-dialog  (for NPAPI). For utilities, you can add a service type  --utility-startup-dialog=data_decoder.mojom.DataDecoderService . You can also try  the vs-chromium plug-in  to attach to the right processes. Semi-automatically attaching the debugger to child processes The following flags cause child processes to wait for 60 seconds in a busy loop for a debugger to attach to the process. Once either condition is true, it continues on; no exception is thrown. --wait-for-debugger-children [=filter] The filter, if provided, will fire only if it matches the  --type  parameter to the process. Values include  renderer ,  plugin  (for NPAPI),  ppapi ,  gpu-process , and  utility . When using this option, it may be helpful to limit the number of renderer processes spawned, using: --renderer-process-limit = 1 Image File Execution Options Using Image File Execution Options (IFEO) will not work because CreateProcess() returns the handle to the debugger process instead of the intended child process. There are also issues with the sandbox. Time travel debugging You can do  time travel debugging using WinDbg Preview  (must be installed from the Microsoft Store). This lets you execute a program forward and backwards. After capturing a trace, you can set breakpoints and step through code as normal, but also provides 'backwards' commands (g-, t-, p-) so that you can go back and forth through the execution. It is especially useful to set data breakpoints ( ba command ) and reverse continuing, so you can see when a certain variable was last changed to its current value. Chromium specifics: The type of injection the time travel tracer needs to perform is incompatible with the Chromium sandbox. In order to record a trace, you'll need to run with  --no-sandbox . Chromium cannot run elevated with Administrator privileges, so the "Launch executable (advance)" option won't work, you'll need to attach after the process has already launched via the checkbox in the bottom right. If you need to record startup-like things, you'll have to use --{browser,gpu,renderer,utility}-startup-dialog, then attach (and hope the relevant code hasn't executed before that point). JsDbg -- data structure visualization You can install  JsDbg as a plugin for WinDbg or Visual Studio . It interactively lets you look at data structures (such as the DOM tree, Accessibility tree, layout object tree, and others) in a web browser as you debug. See the  JsDbg site  for some screen shots and usage examples. This also works when examining memory dumps (though not minidumps), and also works together with time travel debugging. Visual Studio hints Debug visualizers Chrome's custom debug visualizers should be added to the pdb files and automatically picked up by Visual Studio. The definitions are in  //tools/win/DebugVisualizers  if you need to modify them (the BUILD.gn file there has additional instructions). Don't step into trivial functions The debugger can be configured to automatically not step into functions based on regular expression. Edit  default.natstepfilter  in the following directory: For Visual Studio 2015:  C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2015\Visualizers  (for the current user only) For Visual Studio 2017 Pro:  C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\Packages\Debugger\Visualizers  (for all users) or  %USERPROFILE%\My Documents\Visual Studio 2017\Visualizers  (for the current user only) Add regular expressions of functions to not step into. Remember to regex-escape  and  XML-escape them, e.g. < for < and \. for a literal dot. Example: < Function > < Name > operator new </ Name > < Action > NoStepInto </ Action > </ Function > < Function > < Name > operator delete </ Name > < Action > NoStepInto </ Action > </ Function > <!-- Skip everything in std --> < Function > < Name > std::.* </ Name > < Action > NoStepInto </ Action > </ Function > <!-- all methods on WebKit OwnPtr and variants, ... WTF::*Ptr<*>::* --> < Function > < Name > WTF::.*Ptr<.*>::.* </ Name > < Action > NoStepInto </ Action > </ Function > This file is read at start of a debugging session (F5), so you don't need to restart Visual Studio after changing it. More info:  Microsoft email thread V8 and Chromium V8 supports many command-line flags that are useful for debugging. V8 command-line flags can be set via the Chromium command-line flag --js-flags; for instance: chrome.exe --js-flags= "--trace_exception --heap_stats" Note that some V8 command-line flags exist only in the debug build of V8. For a list of all V8 flags try: chrome.exe --js-flags= "--help" Graphics debugging GPU Acceleration of rendering can be more easily debugged with tools. See: Graphics Debugging in Visual Studio 2013 Graphical debugging with NVIDIA NSight Debugging on another machine Sometimes it's useful to debug installation and execution on a machine other than your primary build box. To run the installer on said other machine, first build the mini_installer target on your main build machine (e.g., autoninja -C out\Debug mini_installer). Next, on the debug machine: Make the build machine's build volume available on the debug machine either by mounting it locally (e.g., Z:\) or by crafting a UNC path to it (e.g., \\builder\src) Open up a command prompt and change to a local disk Run src\tools\win\ copy-installer.bat  in the remote checkout by way of the mount (e.g., Z:\PATHTOCHECKOUT\src\...) or UNC path (e.g., \\builder\src\...). This will copy the installer, DLLs, and PDBs into your debug machine's C:\out or C:\build (depending on if you're rocking the component=shared_library build or not) Run  C:\out\Debug\mini_installer.exe  with the flags of your choice to install Chrome. This can take some time, especially on a slow machine. Watch the Task Manager and wait until mini_installer.exe exits before trying to launch Chrome (by way of the shortcut(s) created by the installer) For extra pleasure, add C:\out\Debug to your _NT_SYMBOL_PATH environment variable Consider reading the documentation at the top of copy-installer.bat to see how you can run it. It tries to be smart and copy the right things, but you may need to be explicit (e.g., "copy-installer.bat out Debug"). It is safe to re-run the script to copy only modified files (after a rebuild, for example). You can also use the zip action of the isolate scripts (tools\mb\mb.py) to package all the files for a target into a single zip file, for example: python tools\mb\mb.py zip out/Release base_unittests base_unittests. zip Finding all memory allocations It is possible to use Heap Snapshots to get call stacks on all outstanding allocations that use the OS heap. This works particularly well if heap snapshots are started as soon as the Chrome browser process is created, but before it starts running. Details can be found in  this batch file . However, with  PartitionAlloc Everywhere  most Chromium allocations no longer use the Windows heap so this will only find a subset of allocations, mostly from OS DLLs. Find memory leaks Note: as with Heap Snapshots the utility of UMDH is greatly reduced now because PartitionAlloc Everywhere has mostly replaced the Windows heap. The Windows heap manager has a really useful debug flag, where it can be asked to capture and store a stack trace with every allocation. The tool to scrape these stack traces out of processes is UMDH, which comes with  WinDbg . UMDH is great. It will capture a snapshot of the heap state as many times as you like, and it'll do it fairly quickly. You then run it again against either a single snapshot, or a pair of snapshots, at which time it'll symbolize the stack traces and aggregate usage up to unique stack traces. Turning on the user stack trace database for chrome.exe with gflags.exe makes it run unbearably slowly; however, turning on the user stack trace database on for the browser alone is just fine. While it's possible to turn on the user stack database with the "!gflag" debugging extension, it's too late to do this by the time the initial debugger breakpoint hits. The only reasonable way to do this is to Launch GFlags.exe, Enable the user stack trace database (per image below), Launch Chrome under the debugger. Set a breakpont when chrome.dll loads with "sxe ld chrome.dll". Step up, to allow Chrome.dll to initialize. Disable the stack trace database in GFlags.exe. Continue chrome, optionally detaching the debugger. GFlags.exe settings for user mode stack trace database. If you then ever suffer a browser memory leak, you can snarf a dump of the process with umdh - p :<my browser pid> > chrome-browser-leak-umdh-dump.txt which can then typically be "trivially" analyzed to find the culprit. Miscellaneous Note that by default Application Verifier only works with non-official builds of Chromium. To use Application Verifier on official builds you need to add --disable-features=RendererCodeIntegrity to avoid sandbox crashes in renderer processes. See  crbug.com/1004989  for details. See also  this page . Application Verifier  is a free tool from Microsoft (available as part of the Windows SDK) that can be used to flush out programming errors. Starting with M68 Application Verifier can be enabled for chrome.exe without needing to disable the sandbox. After adding chrome.exe to the list of applications to be stressed you need to expand the list of Basics checks and disable the  Leak  checks. You may also need to disable  Handles  and  Locks  checks depending on your graphics driver and specific Chrome version, but the eventual goal is to have Chrome run with  Handles  and  Locks  checks enabled. When bugs are found Chrome will trigger a breakpoint so running all Chrome processes under a debugger is recommended. Chrome will run much more slowly because Application Verifier puts every heap allocation on a separate page. Note that with PartitionAlloc Everywhere most Chromium allocations don't actually go through the Windows heap and are therefore unaffected by Application Verifier. You can check the undocumented 'Cuzz' checkbox in Application Verifier to get the Windows thread scheduler to add some extra randomness in order to help expose race conditions in your code. To put a breakpoint on CreateFile(), add this break point: {,,kernel32.dll}_CreateFileW@28 {,,kernel32.dll} specifies the DLL (context operator). _ prefix means extern "C". @28 postfix means _stdcall with the stack pop at the end of the function. i.e. the number of arguments in BYTES. You can use  DebugView  from SysInternals or  sawbuck  to view LOG() messages that normally go to stderr on POSIX.

IEEE Computer Graphics and Applications is an active peer-reviewed academic magazine covering information on computer graphics research, technology and applications. It was established in 1981 and is published bi-monthly by the Institute of Electrical and Electronics Engineers. This publication focuses on the research, development, and applications of computer graphics, visualisation, and interactive techniques, covering a broad range of topics, including rendering algorithms, virtual reality, computer animation, visualisation methods, and human-computer interaction. The journal features original research articles, review papers, and technical notes that contribute to the advancement of computer graphics and visualisation technologies. Each issue emphasises innovative algorithms, novel visualisation techniques, and their applications in various domains, fostering knowledge exchange and driving the development of cutting-edge technologies. IEEE Computer Graphics and Applications can be found online at: ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=38 The ISSN is: 0272-1716

IEEE Computer Graphics and Applications is an active peer-reviewed academic magazine covering information on computer graphics research, technology and applications. It was established in 1981 and is published bi-monthly by the Institute of Electrical and Electronics Engineers. This publication focuses on the research, development, and applications of computer graphics, visualisation, and interactive techniques, covering a broad range of topics, including rendering algorithms, virtual reality, computer animation, visualisation methods, and human-computer interaction. The journal features original research articles, review papers, and technical notes that contribute to the advancement of computer graphics and visualisation technologies. Each issue emphasises innovative algorithms, novel visualisation techniques, and their applications in various domains, fostering knowledge exchange and driving the development of cutting-edge technologies. IEEE Computer Graphics and Applications can be found online at: ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=38 The ISSN is: 0272-1716

IEEE Computer Graphics and Applications is an active peer-reviewed academic magazine covering information on computer graphics research, technology and applications. It was established in 1981 and is published bi-monthly by the Institute of Electrical and Electronics Engineers. This publication focuses on the research, development, and applications of computer graphics, visualisation, and interactive techniques, covering a broad range of topics, including rendering algorithms, virtual reality, computer animation, visualisation methods, and human-computer interaction. The journal features original research articles, review papers, and technical notes that contribute to the advancement of computer graphics and visualisation technologies. Each issue emphasises innovative algorithms, novel visualisation techniques, and their applications in various domains, fostering knowledge exchange and driving the development of cutting-edge technologies. IEEE Computer Graphics and Applications can be found online at: ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=38 The ISSN is: 0272-1716

IEEE Computer Graphics and Applications is an active peer-reviewed academic magazine covering information on computer graphics research, technology and applications. It was established in 1981 and is published bi-monthly by the Institute of Electrical and Electronics Engineers. This publication focuses on the research, development, and applications of computer graphics, visualisation, and interactive techniques, covering a broad range of topics, including rendering algorithms, virtual reality, computer animation, visualisation methods, and human-computer interaction. The journal features original research articles, review papers, and technical notes that contribute to the advancement of computer graphics and visualisation technologies. Each issue emphasises innovative algorithms, novel visualisation techniques, and their applications in various domains, fostering knowledge exchange and driving the development of cutting-edge technologies. IEEE Computer Graphics and Applications can be found online at: ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=38 The ISSN is: 0272-1716

IEEE Computer Graphics and Applications is an active peer-reviewed academic magazine covering information on computer graphics research, technology and applications. It was established in 1981 and is published bi-monthly by the Institute of Electrical and Electronics Engineers. This publication focuses on the research, development, and applications of computer graphics, visualisation, and interactive techniques, covering a broad range of topics, including rendering algorithms, virtual reality, computer animation, visualisation methods, and human-computer interaction. The journal features original research articles, review papers, and technical notes that contribute to the advancement of computer graphics and visualisation technologies. Each issue emphasises innovative algorithms, novel visualisation techniques, and their applications in various domains, fostering knowledge exchange and driving the development of cutting-edge technologies. IEEE Computer Graphics and Applications can be found online at: ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=38 The ISSN is: 0272-1716

IEEE Computer Graphics and Applications is an active peer-reviewed academic magazine covering information on computer graphics research, technology and applications. It was established in 1981 and is published bi-monthly by the Institute of Electrical and Electronics Engineers. This publication focuses on the research, development, and applications of computer graphics, visualisation, and interactive techniques, covering a broad range of topics, including rendering algorithms, virtual reality, computer animation, visualisation methods, and human-computer interaction. The journal features original research articles, review papers, and technical notes that contribute to the advancement of computer graphics and visualisation technologies. Each issue emphasises innovative algorithms, novel visualisation techniques, and their applications in various domains, fostering knowledge exchange and driving the development of cutting-edge technologies. IEEE Computer Graphics and Applications can be found online at: ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=38 The ISSN is: 0272-1716

IEEE Computer Graphics and Applications is an active peer-reviewed academic magazine covering information on computer graphics research, technology and applications. It was established in 1981 and is published bi-monthly by the Institute of Electrical and Electronics Engineers. This publication focuses on the research, development, and applications of computer graphics, visualisation, and interactive techniques, covering a broad range of topics, including rendering algorithms, virtual reality, computer animation, visualisation methods, and human-computer interaction. The journal features original research articles, review papers, and technical notes that contribute to the advancement of computer graphics and visualisation technologies. Each issue emphasises innovative algorithms, novel visualisation techniques, and their applications in various domains, fostering knowledge exchange and driving the development of cutting-edge technologies. IEEE Computer Graphics and Applications can be found online at: ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=38 The ISSN is: 0272-1716

The Executive Information Services (EIS) system, developed as a computer-based, time-sharing tool for making and implementing management decisions, and including computer graphics capabilities, was described. The following resources are available through the EIS languages: centralized corporate/gov't data base, customized and working data bases, report writing, general computational capability, specialized routines, modeling/programming capability, and graphics. Nearly all EIS graphs can be created by a single, on-line instruction. A large number of options are available, such as selection of graphic form, line control, shading, placement on the page, multiple images on a page, control of scaling and labeling, plotting of cum data sets, optical grid lines, and stack charts. The following are examples of areas in which the EIS system may be used: research, estimating services, planning, budgeting, and performance measurement, national computer hook-up negotiations.

Six computer applications packages have been developed to solve a variety of aerodynamic problems in an interactive environment on a single workstation. The packages perform classical one dimensional analysis under the control of a graphical user interface and can be used for preliminary design or educational purposes. The programs were originally developed on a Silicon Graphics workstation and used the GL version of the FORMS library as the graphical user interface. These programs have recently been converted to the XFORMS library of X based graphics widgets and have been tested on SGI, IBM, Sun, HP and PC-Lunix computers. The paper will show results from the new VU-DUCT program as a prime example. VU-DUCT has been developed as an educational package for the study of subsonic open and closed loop wind tunnels.

Six computer applications packages have been developed to solve a variety of aerodynamic problems in an interactive environment on a single workstation. The packages perform classical one dimensional analysis under the control of a graphical user interface and can be used for preliminary design or educational purposes. The programs were originally developed on a Silicon Graphics workstation and used the GL version of the FORMS library as the graphical user interface. These programs have recently been converted to the XFORMS library of X based graphics widgets and have been tested on SGI, IBM, Sun, HP and PC-Lunix computers. The paper will show results from the new VU-DUCT program as a prime example. VU-DUCT has been developed as an educational package for the study of subsonic open and closed loop wind tunnels.

Six computer applications packages have been developed to solve a variety of aerodynamic problems in an interactive environment on a single workstation. The packages perform classical one dimensional analysis under the control of a graphical user interface and can be used for preliminary design or educational purposes. The programs were originally developed on a Silicon Graphics workstation and used the GL version of the FORMS library as the graphical user interface. These programs have recently been converted to the XFORMS library of X based graphics widgets and have been tested on SGI, IBM, Sun, HP and PC-Lunix computers. The paper will show results from the new VU-DUCT program as a prime example. VU-DUCT has been developed as an educational package for the study of subsonic open and closed loop wind tunnels.

Six computer applications packages have been developed to solve a variety of aerodynamic problems in an interactive environment on a single workstation. The packages perform classical one dimensional analysis under the control of a graphical user interface and can be used for preliminary design or educational purposes. The programs were originally developed on a Silicon Graphics workstation and used the GL version of the FORMS library as the graphical user interface. These programs have recently been converted to the XFORMS library of X based graphics widgets and have been tested on SGI, IBM, Sun, HP and PC-Lunix computers. The paper will show results from the new VU-DUCT program as a prime example. VU-DUCT has been developed as an educational package for the study of subsonic open and closed loop wind tunnels.

Six computer applications packages have been developed to solve a variety of aerodynamic problems in an interactive environment on a single workstation. The packages perform classical one dimensional analysis under the control of a graphical user interface and can be used for preliminary design or educational purposes. The programs were originally developed on a Silicon Graphics workstation and used the GL version of the FORMS library as the graphical user interface. These programs have recently been converted to the XFORMS library of X based graphics widgets and have been tested on SGI, IBM, Sun, HP and PC-Lunix computers. The paper will show results from the new VU-DUCT program as a prime example. VU-DUCT has been developed as an educational package for the study of subsonic open and closed loop wind tunnels.

The main objective of the course (through the lectures and through these notes) is to provide enough background on wavelets so that a researcher or skilled practitioner in computer graphics can understand the nature and properties of wavelets, and assess their suitability to solve specific problems in computer graphics. Our goal is that after the course and/or the study of these notes one should be able to access the basic mathematical literature on wavelets, understand and review critically the current computer graphics literature using them, and have some intuition about the pluses and minuses of wavelets and wavelet transform for a specific application. Lecture Notes Collection FreeScience.info ID2638 Obtained from http://www.multires.caltech.edu/teaching/courses/waveletcourse/sig95.course.pdf http://www.freescience.info/go.php?pagename=books&id=2638

The main objective of the course (through the lectures and through these notes) is to provide enough background on wavelets so that a researcher or skilled practitioner in computer graphics can understand the nature and properties of wavelets, and assess their suitability to solve specific problems in computer graphics. Our goal is that after the course and/or the study of these notes one should be able to access the basic mathematical literature on wavelets, understand and review critically the current computer graphics literature using them, and have some intuition about the pluses and minuses of wavelets and wavelet transform for a specific application. Lecture Notes Collection FreeScience.info ID2638 Obtained from http://www.multires.caltech.edu/teaching/courses/waveletcourse/sig95.course.pdf http://www.freescience.info/go.php?pagename=books&id=2638

The main objective of the course (through the lectures and through these notes) is to provide enough background on wavelets so that a researcher or skilled practitioner in computer graphics can understand the nature and properties of wavelets, and assess their suitability to solve specific problems in computer graphics. Our goal is that after the course and/or the study of these notes one should be able to access the basic mathematical literature on wavelets, understand and review critically the current computer graphics literature using them, and have some intuition about the pluses and minuses of wavelets and wavelet transform for a specific application. Lecture Notes Collection FreeScience.info ID2638 Obtained from http://www.multires.caltech.edu/teaching/courses/waveletcourse/sig95.course.pdf http://www.freescience.info/go.php?pagename=books&id=2638

2004 by Idea Group Inc. All

Finite element analyses of two and three dimensional structures often require the use of curved isoparametric elements. The overall effectiveness of such analyses by large scale finite element computer programs is often handicapped by the costly and tedious job of verifying input data and the lack of a comprehensive graphical presentation of the output. This contract work involved mathematical research concerning various approaches to improving this pre- and post processing of finite element data utilizing interactive computer graphics. A key aspect of this work was the characterization of the existence of the inverses of isoparametric mappings, as well as the development of efficient algorithms for the numerical inversion of such mappings. (Author)

Spatial queries are a fundamental class of queries on geographic data that consist primarily of points, lines, and polygons. Enhancing response time of spatial queries requires a spatial index. The chaintree is a dynamic spatial index structure being developed at RAND, based on a regular planar straight line graph. The chaintree organizes polygons to efficiently answer spatial queries. An operation basic to most chaintree procedures is polygon intersection. This Note presents a new algorithm for finding the intersection of two uniformly monotone polygons in linear time and space without preprocessing.

1Uncle Remus

By Joel Chandler Harris

Many readers will already be familiar with Uncle Remus’ favorite animal characters – Br’er Rabbit and Br’er Fox among them – and some of the popular tales concerning them. (To this day, “tar baby” as an expression for a particularly sticky situation that is almost impossible to solve, has passed into the English language and common use.) Even people who have never read any of these tales will know exactly why you don’t throw a rabbit into a briar patch, mainly because Walt Disney produced his first movie ever to use professional actors with animation, called “Song of the South”, based on the Uncle Remus tales.<br /><br /> Joel Chandler Harris, a newsman in Georgia, grew up listening to folktales told by the local black population. Later, he published his version of these tales in a series of stories printed in the “Atlanta Constitution.” The tales of, and by, Harris’ chief character Uncle Remus, an old black man scrabbling to make his living in the post-Civil War South, were extremely popular and widely read. Harris’ use of innovative spelling to give the reader a sense of the black dialect was considered novel.<br /><br /> While this is not a book that will pass a current political correctness test, due to its use of labels for black folks which have gone out of polite conversation, Uncle Remus is a largely sympathetic look at post-war plantation life. Uncle Remus himself is a warm, folksy man of good humor and dry wit, and after finishing his animal stories, the remaining sayings and tales are a moment of history frozen in amber. (Summary by Mark)

2Life in a Thousand Worlds

By William Shuler Harris

A jolly romp, which could be perhaps be described as Gulliver’s Travels Through Our Solar System and Beyond, as written by a great admirer of C. S. Lewis, on a rainy Sunday afternoon, after one too many mugs of cocoa. Includes some thought on alien philosophies and how to apply them to moral and social problems here on Planet Earth.<br><br> Unrelated to the book, this was also the one-thousandth project to be started at LibriVox. — (Non-summary by Cori Samuel.)

3Oscar Wilde: His Life and Confessions

By Frank Harris

Consumers of biography are familiar with the division between memoirs of the living or recently dead written by those who "knew" the subject more or less intimately, and the more objective or scholarly accounts produced by later generations.<br /><br /> In the case of Wilde, as presented to us by Frank Harris, we are in a way doubly estranged from the subject. We meet with Oscar the charismatic talker, whose tone of voice can never be reproduced – even if a more scrupulous biographer had set down his words accurately – and we are perhaps already aware of him as Wilde the self-destructive celebrity who uneasily fills the place of the premier gay icon and martyr in our contemporary view.<br /><br /> Neither of these images will do. We need to read as many accounts as possible. Harris, though himself a self-advertising literary and sexual buccaneer, takes a wincingly representative view of Wilde’s homophile activity: for him it is a patrician excrescence, the abominable vice of the few, contracted at English boarding schools – though thankfully “not infectious” as far as he himself is concerned.<br /><br /> What a long road we have to travel to arrive at the essentially gay man of today! But there are many shortcuts to take us back to where we came from… (Summary by Martin Geeson)

4Uncle Remus and Brer Rabbit

By Joel Chandler Harris

Uncle Remus' stories feature a trickster hero called Br'er Rabbit ("Brother" Rabbit), who uses his wits to slide out of trouble and gain the advantage over the slower witted other animals, many of whom are trying to eat him. Br'er Rabbit stories were mostly collected directly from the afro-american oral story-telling tradition and are said to be a direct interpretation of Yoruba tales of Hare. This book contains 11 unique stories and was the last one published before the author's death. (Introduction by Phil Chenevert)

5Nights With Uncle Remus

By Joel Chandler Harris

That the little boy loved Uncle Remus and his stories was so obvious that the tale-spinning sessions began drawing additional listeners. Daddy Jack, an old "Africa man" visiting from down-state; Sis Tempy, the strong chief of the mansion's servants; and Tildy, a young and pretty servant-girl - all found their way to Uncle Remus' rude cabin when their duties or interests permitted, to sit around the hearth and hear the wonderful tales of the animals, and foremost among them, Brer Rabbit and Brer Fox.<br></br>It turned out that some of the tales had different ways of telling, and the visitors took their turns at being the story-teller. Always one or more clever animals humbled or hornswoggled others among their community with flattery, wide-eyed mystery, or outright fraud.<br></br>After the success of Harris' "Uncle Remus: His Songs and His Sayings" ( http://librivox.org/uncle-remus-by-joel-chandler-harris/ ), he went on to write eight more books compiling the tales he himself had heard on the plantation in his young days. This is the first of those sequels.

The recollections of a British infantryman who served in the British army during the Napoleonic Wars. (Summary by Graham Keeling)

26 of Uncle Remus's stories put into verse and song. With the exception of the Tar Baby story, they were all new to this publication of 1904 and cover a variety of humorous subjects from Adan and Eve (De Appile Tree) to Brer Rabbit's Gigglin' Place. There are also genuine Camp Meeting Songs and a Corn Shuckin' Song. (Summary by Phil Chenevert)

Uncle Remus tells these 11 stories but to the son of the original "little boy" who is visiting his grandmother on the plantation. As always Uncle Remus can be relied upon to provide funny and pointed insight into human personalities through his story telling. These were all published in the Uncle Remus magazine from 1905 and 1906 and gathered together in this book by the author. (Summary by Phil Chenevert)

9Uncle Remus & Friends

By Joel Chandler Harris

Uncle Remus, that genial old storyteller, knows how to spin these wonderful tales about the 'criteers' that the little 6 year old boy (and many of us adults!) love to listen to. Yet the 'Brer Rabbit and 'Brer Fox and the others sound a lot like the people all around us. They tell stories about personalities and faults and virtues in a way that is unique to Uncle Remus. As the shadows grow longer outside, draw up a rocking chair next to the little boy, settle back and listen to the wise old man tell these stories. These 17 stories were specially chosen from Uncle Remus: His Songs and Sayings and include The Wonderful Tar-Baby Story, Miss Cow falls a Victim to Mr. Rabbit; Mr. Fox and the Deceitful Frogs; Mr. Rabbit grossly deceives Mr. Fox and lots of others. (Summary by phil chenevert)

While detective work always makes for exciting stories, the circumstances under which the detective works play a huge role in the thrill. The stories in this collection follow detectives as they unravel mysteries in times of war, where danger awaits them at every turn. - Summary by Carolin

11Honey-Bee: Its Nature, Homes and Products

By William Hetherington Harris

"In these days of intense business-pressure, it is a good thing for men to cultivate hobbies. We say this, notwithstanding the fact that men with hobbies are likely to become bores, from thinking and talking too incessantly of their pet occupations, or are apt to run into extravagant expenditure of time and money, which could be better utilised. Now, in recommending apiculture, or bee-keeping, as a recreation from more serious pursuits, we feel that we incur little risk of increasing the number of bores in society, or of inducing an undue outlay of hours or pounds on the part of those who follow our suggestions. For, on the one hand, the facts likely to be spoken of by enthusiastic apiarians to casual hearers could not fail to interest; while the practical results of bee-keeping will certainly, to say the least, repay in hard cash all reasonable outlay on the part of any one who is possessed of ordinary good sense, and who learns to manage his hives according to modern methods." - From the book Introduction

An allegory that describes the sad journey of Miss Church-Member who thinks she is traveling on a more convenient way to heaven, but she does not realize that she is traveling on the Broad Highway to destruction with her polite, yet, fiendish companion, Mr. World. - Summary by James En

The Guerra del Rif—the Rif War. 1921 to 1926. It was the slogging bloody 5-year long climax of Spain’s effort to secure dominion over a territory in North Africa allotted them by France; A chapter instigated over a cause no less profane than a mining concession and which would prove to be an unmitigated disaster for all involved; the Spanish, the French and the Iriffiyen. <br><br> This attempted salve for a nation’s wounded prestige would leave more than forty thousand Spaniards as casualties, the nation humiliated and irrevocably destabilize the Spanish state—directly leading to the dethronement of Alfonso XIII, civil war and the rise of Franco. The French Republic would be sucked into the conflict while enforcing their own colonial designs on Morocco and would suffer—only—eighteen thousand casualties. The war evoked widespread condemnation from the left in France and provided an exemplar for anti-colonial revolt which would go on to haunt them for many decades hence. <br><br> Finally, Abd El-Krim’s Republic of the Rif would (eventually) be crushed under the weight of an opposing army of almost half-a-million soldiers as well as hundreds of tanks and aircraft. During the war, the Spanish and French widely employed chemical weapons against Rifian civilian populations. As a side note, also during the war Spain and France signed the Geneva Protocol prohibiting the use of chemical weapons—though the treaty didn’t come into effect until 1928. <br><br> <i>⸮ It is one thing to make a stand on moral principle, after all, but quite another to let perfectly good stockpiles of phosgene and mustard gas go to waste.~</i> <br><br> Throughout the duration of this particularly brutal and senseless war the correspondent covering it for The Times was Walter Burton Harris, British expat and author of this book, who had deep connections in Morocco having settled there in 1887 and travelled widely within the country. <br><br> This is his account. - Summary by Alister<br><br> <b>Part 2</b> can be found at: <a href="https://librivox.org/france-spain-and-the-rif-part-2-by-walter-burton-harris/">https://librivox.org/france-spain-and-the-rif-part-2-by-walter-burton-harris/</a>

14Story of Coventry

By Mary Dormer Harris

Nowadays best known for its bombing in WWII, the English city of Coventry was founded in the early Middle Ages. Earl Leofric and his wife Lady Godiva (famously riding naked through the streets) founded a Benedictine monastery in 1043, and over time, the city became a major pilgrimage center. During the Wars of the Roses (1455 - 1487), the Royal Court was moved to Coventry and parliament was held in the city as well. In this book Mary Dormer Harris follows Coventry's history through the Middle Ages. While looking at famous people from Coventry and their influence on the city's architecture, she also details the daily lives of the common townsfolk, the guild, and their contributions to the city's thriving economy. This book is part of the "Mediaeval Town" series published in the early 20th century. (Summary by Availle)

The Guerra del Rif—the Rif War. 1921 to 1926. It was the slogging bloody 5-year long climax of Spain’s effort to secure dominion over a territory in North Africa allotted them by France; A chapter instigated over a cause no less profane than a mining concession and which would prove to be an unmitigated disaster for all involved; the Spanish, the French and the Iriffiyen. <br><br> This attempted salve for a nation’s wounded prestige would leave more than forty thousand Spaniards as casualties, the nation humiliated and irrevocably destabilize the Spanish state—directly leading to the dethronement of Alfonso XIII, civil war and the rise of Franco. The French Republic would be sucked into the conflict while enforcing their own colonial designs on Morocco and would suffer—only—eighteen thousand casualties. The war evoked widespread condemnation from the left in France and provided an exemplar for anti-colonial revolt which would go on to haunt them for many decades hence. <br><br> Finally, Abd El-Krim’s Republic of the Rif would (eventually) be crushed under the weight of an opposing army of almost half-a-million soldiers as well as hundreds of tanks and aircraft. During the war, the Spanish and French widely employed chemical weapons against Rifian civilian populations. As a side note, also during the war Spain and France signed the Geneva Protocol prohibiting the use of chemical weapons—though the treaty didn’t come into effect until 1928. <br><br> <i>⸮ It is one thing to make a stand on moral principle, after all, but quite another to let perfectly good stockpiles of phosgene and mustard gas go to waste.~</i> <br><br> Throughout the duration of this particularly brutal and senseless war the correspondent covering it for The Times was Walter Burton Harris, British expat and author of this book, who had deep connections in Morocco having settled there in 1887 and travelled widely within the country. <br><br> This is his account. - Summary by Alister<br><br> <b>Part 1</b> can be found at: <a href="https://librivox.org/france-spain-and-the-rif-part-1-by-walter-burton-harris/">https://librivox.org/france-spain-and-the-rif-part-1-by-walter-burton-harris/</a>

Wholesome Cooking, A Practical Book for a Practical Cook, Two Hundred Well-Tested Recipes selected by Ethel Harris. Ten chapters from soup to cakes with such intriguing dishes as rabbit stew, fricassee parsnips, and snow pudding. Recipes are given in the older narrative style with general instructions for each type of dish. - Summary by Larry Wilson

17Persephone of Eleusis

By Clare Winger Harris

A romance of Ancient Greece featuring the hero's journey and evil plotting. Will either succeed? - Summary by Christine Rottger