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b5af88a563
The `info line` in particular was given by Ell and will make trace
handling a lot easier as it means we may not have to ask for traces with
debug symbols or gdb with Flatpak. We can indeed get these infos back
ourselves since we are guaranted to use the exact same binaries.
This together with the change in verbose version output I did 2 weeks
ago (commit bc5f6371e9), allowing us to check the exact Flatpak hash
commit used by a reporter, Flatpak debugging should be a lot easier with
just the simpler stack trace format.
186 lines
6.2 KiB
Text
186 lines
6.2 KiB
Text
There are a few environment variables, options or other more-or-less
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known tricks to debug GIMP. Let's try to add them here for reminder and
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newcomers.
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## Basics ##
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The basic thing is to build babl, GEGL and GIMP with `--enable-debug`.
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Note that if you also built glib from source with `--enable-debug`,
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every GObject destroyed are apparently overwritten with values invalid
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as pointers, so dereferencing one after destruction usually leads to a
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crash, which is a good way to find some more vicious bugs.
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## Debug logs ##
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You can see various GIMP_LOG() calls in the code. These will only be
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outputted when you set GIMP_DEBUG environment variable to a
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comma-separated list of domain.
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For instance, for `GIMP_LOG (XCF, "some string")` to be outputted,
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run GIMP like this:
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> GIMP_DEBUG=xcf gimp-2.10
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Special flags are:
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- "all" to output all domain logs;
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- "list-all" to get a list of available domains.
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## Debugging a warning ##
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If you encounter a CRITICAL or WARNING message on console, you can make
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so that GIMP crashes on it, which will make it very easy to be tracked
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down in a debugger (for instance GDB), by running GIMP with:
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> gimp-2.10 --g-fatal-warnings
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Note that if all you want is a stacktrace, it is not necessary anymore
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to use a debugger and --g-fatal-warnings. In Preferences > Debugging,
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make sure that all type of errors are debugged, and that you have either
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gdb or lldb installed. Then a graphical dialog will automatically appear
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upon encountering any WARNING or CRITICAL with backtraces and variable
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contents.
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Alternatively running GIMP with the CLI option --stack-trace-mode to
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values "query" or "always" will output a stacktrace too on terminal.
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But this happens only for crashes, so it still requires to use
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--g-fatal-warnings for WARNINGs and CRITICALs.
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Note: on Windows, even the debugging GUI happens only for crashes and
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requires that you built with Dr. Mingw dependency.
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## Debugging GTK+ ##
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You can use GtkInspector by running GIMP with:
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> GTK_DEBUG=interactive gimp-2.99
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Alternatively you may also start it at anytime with ctrl-shift-d
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shortcut, if you first enable with:
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> gsettings set org.gtk.Settings.Debug enable-inspector-keybinding true
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See also: https://wiki.gnome.org/Projects/GTK%2B/Inspector
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## Debugging GEGL code ##
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You may encounter this kind of warning upon exiting GIMP:
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> EEEEeEeek! 2 GeglBuffers leaked
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To debug GeglBuffer leaks, make sure you built GEGL with -Dbuildtype=debug
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or -Dbuildtype=debugoptimized, and set the environment variable
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GEGL_DEBUG to "buffer-alloc".
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Your system also needs to have the header "execinfo.h".
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## Debugging babl ##
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Profile conversion is done with babl by default when possible, which is
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much faster.
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Setting GIMP_COLOR_TRANSFORM_DISABLE_BABL environment variable switch
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back to the old lcms implementation, which can be useful for comparison.
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## Debugging X Window System error ##
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Make X calls synchronous so that your crashes happen immediately with:
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> gimp-2.10 --sync
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You can also break on `gdk_x_error()`.
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## Debugging on Windows ##
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Even when run from a `cmd`, the standard and error outputs are not
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displayed in the terminal. For this reason, unstable builds (i.e. with
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odd minor version) pop up a debug console at start.
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If you are building stable versions of GIMP for debugging and want this
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debug console as well, configure with `--enable-win32-debug-console`.
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## Testing older GIMP versions ##
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A useful trick when you want to quickly test a specific GIMP older
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version (e.g. to confirm a behavior change) is to install it with our
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official flatpak. The flathub repository stores past builds (up to 20 at
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the time of writing). You can list them with the following command:
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```
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$ flatpak remote-info --log flathub org.gimp.GIMP
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```
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Each build will have a "Subject" line (a comment to indicate the build
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reason, it may be just dependency updates or build fixes, or sometimes a
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bump in GIMP version) and a commit hash. When you have identified the
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build you want to test, update it like this:
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```
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flatpak update --commit=<hash-of-build> org.gimp.GIMP
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```
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Then just run your older GIMP!
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## Debugging on flatpak
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If you want to inspect the sandbox environment, you can do so by
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specifying a custom shell instead of the GIMP binary with the following
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command:
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```
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flatpak run --command=bash org.gimp.GIMP
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```
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This will run the exact same environment as the flatpak, which should
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also be identical on all machines.
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Alternatively you can run the GIMP Flatpak using the GNOME SDK as
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runtime (instead of the .Platform) with the `--devel` option. In
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particular, it gives you access to a few additional debug tools, such as
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`gdb`. Therefore running GIMP with --devel will give better stacktrace,
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or you can run explicitly GIMP inside GDB.
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Additionally to install debug symbols in the sandbox, run:
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```
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flatpak install flathub org.gimp.GIMP.Debug
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flatpak install flathub org.gnome.Sdk.Debug
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```
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Finally even with reporter trace without debug symbols (yet debug
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symbols installed on your side), if you make sure you use exactly the
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same flatpak commit as the reporter (see `Testing older GIMP versions`
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section), you are ensured to use the same binaries. Hence you can trace
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back the code line from an offset.
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For instance, say that your trace has this output:
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```
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gimp-2.10(file_open_image+0x4e8)[0x5637e0574738]
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```
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Here is how you can find the proper code line in the Flatpak (provided
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you use the right flatpak commit):
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```
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$ flatpak install flathub org.gimp.GIMP.Debug org.gnome.Sdk.Debug
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$ flatpak run --devel --command=bash org.gimp.GIMP
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(flatpak) $ gdb /app/bin/gimp-2.10
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(gdb) info line *(file_open_image+0x4e8)
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Line 216 of "file-open.c" starts at address 0x4d5738 <file_open_image+1256> and ends at 0x4d5747 <file_open_image+1271>.
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```
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## Debugging icons ##
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See file `devel-docs/icons.txt` to learn more about our icons, and in
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particular the environment variable GIMP_ICONS_LIKE_A_BOSS.
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## Debugging plug-ins ##
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See file `devel-docs/debug-plug-ins.txt` for usage of environment
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variable GIMP_PLUGIN_DEBUG.
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The CLI option --stack-trace-mode also applies to plug-ins, in order to
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output a back trace on terminal.
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## Performance logs ##
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See file `devel-docs/performance-logs/performance-logs.md` for information
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about GIMP performance logs, which can help during optimization.
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