177 lines
7.3 KiB
Plaintext
177 lines
7.3 KiB
Plaintext
Debugging i3: How To
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====================
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Michael Stapelberg <michael@i3wm.org>
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January 2014
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This document describes how to debug i3 to send us useful bug
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reports, even if you have no knowledge of C programming.
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Thank you for being interested in debugging i3. It really means
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something to us to get your bug fixed. If you have any questions about the
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process and/or need further help, do not hesitate to contact us!
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== Verify you are using i3 ≥ 4.10
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Only the latest major version of i3 is supported. To verify which version
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you are running, use:
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---------------
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$ i3 --moreversion 2>&- || i3 --version
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Binary i3 version: 4.7 (2013-12-22, branch "tags/4.7")
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Running i3 version: 4.7-84-gac74a63 (2014-01-01, branch "next") (pid 1995)
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---------------
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Your version can look like this:
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4.7 (release version)::
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You are using a release version. In many cases, bugs are already
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fixed in the development version of i3. Even if the bug is not a known fixed
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one, we will still ask you to reproduce your error with the most recent
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development version of i3. Therefore, please upgrade to a development version
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if you can.
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4.7-85-g9c15b95 (development version)::
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Your version is 85 commits newer than 4.7, and the git revision of your
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version is +9c15b95+. Go to https://github.com/i3/i3/commits/next and see if
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the most recent commit starts with the same revision. If so, you are using the
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latest version.
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Development versions of i3 have logging enabled by default and are compiled
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with debug symbols.
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== Enabling logging
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If you are using a development version (see previous section), you don’t need
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to do anything -- skip to section 3.
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If you are using a release version with a custom +~/.xsession+ (or xinitrc)
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file, execute i3 with a line like this:
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----------------------------------
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# Use 25 MiB of RAM for debug logs
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exec i3 --shmlog-size=26214400
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----------------------------------
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If you are *NOT* using an +~/.xsession+ file but you just chose "i3" from the
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list of sessions in your desktop manager (gdm, lxdm, …), edit
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+/usr/share/xsessions/i3.desktop+ and replace the +Exec=i3+ line with:
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------------------------------
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Exec=i3 --shmlog-size=26214400
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------------------------------
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If you cannot restart i3 for some reason, you can enable debug logging on the
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fly:
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---------------------------------------
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i3-msg 'debuglog on; shmlog on; reload'
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---------------------------------------
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== Reproducing the problem
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Before submitting an issue, please make sure to close down on the problem as
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much as you can yourself. Here are some steps you should consider:
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* Find a deterministic, reliable way to reproduce the problem and provide it
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with your bug report.
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* Try using the default i3 config to reproduce the problem. If the issue does
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not appear with the default config, gradually adapt it to track down what
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change(s) to the config introduce the problem.
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* Reproduce the problem with a minimal setup, i.e., only use as few applications,
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windows and steps as necessary.
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* In addition, try to stick to applications that are common and, even more
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importantly, free / open source.
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* Before obtaining the log file, restart i3 in-place, execute the steps to
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reproduce the problem and then save the logs. This keeps the log file as
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small as possible and necessary.
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Please be aware that we cannot support compatibility issues with closed-source
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software, as digging into compatibility problems without having access to the
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source code is too time-consuming. Additionally, experience has shown that
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often, the software in question is responsible for the issue. Please raise an
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issue with the software in question, not i3.
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== Obtaining the debug logfile
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[CAUTION]
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================================================================================
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Logs may contain sensitive information, so please inspect the log before
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submitting it. Logs may be viewed by anyone, once posted. If you choose to
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redact the log, make an effort not to discard information which may be relevant
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to the issue you are reporting.
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The best way to avoid submitting such information is to only run the necessary
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steps to reproduce the behavior when saving the log file. This will also make
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analyzing the log file easier.
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================================================================================
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No matter whether i3 misbehaved in some way without crashing or whether it just
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crashed, the logfile provides all information necessary to debug the problem.
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To upload a compressed version of the logfile (for a bugreport), use:
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-------------------------------------------------------------------------------
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DISPLAY=:0 i3-dump-log | bzip2 -c | curl --data-binary @- https://logs.i3wm.org
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-------------------------------------------------------------------------------
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This command does not depend on i3 (it also works while i3 displays
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the crash dialog), but it requires a working X11 connection.
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After running it, you will get a URL to the logfile. Please include that URL in
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your bug report.
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== On crashes: Obtaining a backtrace
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When i3 crashes, it will display a dialog stating “i3 just crashed”, offering
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you to save a backtrace to a text file.
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To actually get useful backtraces, you should make sure that your version of i3
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is compiled with debug symbols:
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------------------------------------------------------------------------------
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$ file `which i3`
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/usr/bin/i3: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically
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linked (uses shared libs), for GNU/Linux 2.6.18, not stripped
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------------------------------------------------------------------------------
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Notice the +not stripped+, which is the important part. If you have a version
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which is stripped, please check whether your distribution provides debug
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symbols (package +i3-wm-dbg+ on Debian for example) or if you can turn off
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stripping. If nothing helps, please build i3 from source.
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Once you have made sure that your i3 is compiled with debug symbols and the C
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debugger +gdb+ is installed on your machine, you can let i3 generate a
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backtrace in the crash dialog.
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After pressing "b" in the crash dialog, you will get a file called
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+/tmp/i3-backtrace.%d.%d.txt+ where the first +%d+ is replaced by i3’s process
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id (PID) and the second one is incremented each time you generate a backtrace,
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starting at 0.
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== Sending bug reports/debugging on IRC
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When sending bug reports, please attach the *whole* log file. Even if you think
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you found the section which clearly highlights the problem, additional
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information might be necessary to completely diagnose the problem.
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When debugging with us in IRC, be prepared to use a so-called nopaste service
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such as https://pastebin.com because pasting large amounts of text in IRC
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sometimes leads to incomplete lines (servers have line length limitations) or
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flood kicks.
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== Debugging i3bar
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To debug i3bar problems, add +verbose yes+ to all +bar {}+ blocks in your i3
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config, reload your config and then restart all i3bar instances like this:
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---------------------------------------------------------------------
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$ i3 reload
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$ killall i3bar
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$ for c in $(i3-msg -t get_bar_config | python -c \
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'import json,sys;print("\n".join(json.load(sys.stdin)))'); do \
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(i3bar --bar_id=$c >i3bar.$c.log 2>&1) & \
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done;
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---------------------------------------------------------------------
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There will now be +i3bar.*.log+ files in your current directory that you can provide
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in your bug report.
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