Creating Backtraces

Creating back-traces for debugging

Found a crash? Generate a back-trace so we can see exactly where Mixxx crashed.

Windows

Download GDB for Windows (get the official release version) and save it to the root of your C: drive. (C:\)
Download Mixxx's debug symbol file:
1. 32-bit: FIXME
2. 64-bit: FIXME
Open a Windows prompt:

Win 7: Open a command prompt by clicking Start->Run... then type cmd in the box and press Enter.
Win 10: Type cmd to the task bar search box and press Enter

Change to the the directory where Mixxx is installed: type the following then press Enter: cd %PROGRAMFILES%\Mixxx
Run GDB: type the following command and press Enter: C:\gdb mixxx.exe
Load optional debug symbols *.pdb installed on your system. add-symbol-file mixxx.pdb
Continue below

Linux & Mac OS X with Xcode 4.x

From a command prompt/terminal, type "gdb mixxx" and press Enter.

OSX users need to specify the path for the executable file, e.g gdb /Applications/Mixxx.app/Contents/MacOS/mixxx
Use the gdb "--args" option to pass arguments, e.g. gdb --args ./mixxx --controllerDebug --developer --resourcePath res

Continue below

For all of the above

When the gdb prompt appears, type set height 0 and press enter to disable screen paging.
Type run and press enter.
Make Mixxx crash. When it does, type the following into the gdb prompt: thread apply all bt. (There may be multiple pages of output. Make sure to hit <Enter> enough times to see it all.)
To close the Mixxx window and end gdb, type the following into the gdb prompt: quit
Copying the gdb info:

Windows users can copy the terminal buffer into a text file:
1. Click the window's icon in the top left corner.
2. Choose Edit-->Select All. Everything selected will be inverted (so black becomes white, white becomes black, etc) Note: a Windows console will not update while any part of it is selected.
3. Press Enter to copy the selection to the clipboard and de-select everything.
4. Paste the clipboard buffer into a Notepad text document.
5. Attach that to a bug report. (See below.)
Linux/OSX users should be able to select terminal output by using the mouse, and then doing a right click and selecting Copy.

Report a bug using the Mixxx bug reporting system on Launchpad. Bugs filed here are tracked by developers and will not fall through the cracks as easily as using the IRC channel or mixxx-devel. (If another bug matches your issue, please make a comment on that one including your system details instead of filing a new bug.) Make sure to attach your back-trace (click Add attachment or patch.) Do not paste it in the comment.
If you do not want to use Launchpad, post the results in the forum, email them to mixxx-devel, or pastebin them and drop the link on IRC. We'll then try to figure out where the crash is. Do not assume a developer will hear you in IRC, using a static system (bug tracker, e-mail, forum) is much preferred. The IRC channel is great for technical support though.

Note: To get a backtrace for a thread freeze you can do the same thing as above, but to get the gdb prompt, you have to press CTRL+Z in the terminal window to suspend Mixxx.

Mac OS X with Xcode 5.x

Apple switched to clang/lldb. Xcode 5 does not include the GNU compiler or tools.

Open a terminal window.
Specify the path for the executable file

lldb /Applications/Mixxx.app/Contents/MacOS/mixxx
lldb output should read Current executable set to '/Applications/Mixxx.app/Contents/MacOS/mixxx' (x86_64)
If want to pass flag-like arguments to Mixxx, you have to terminate the actual flags with "--" lldb -- ./mixxx --controllerDebug --developer --resourcePath res

At the lldb prompt, type run and press enter.
Make Mixxx crash.
When it does, type the following into the lldb prompt: thread backtrace all
To close the Mixxx window and end lldb, type the following at the lldb prompt: quit
Copy the lldb output. Select the terminal output by using the mouse, and then doing a right click and selecting Copy

For more informations, go to http://lldb.llvm.org/lldb-gdb.html

Windows: creating a dump file

When reporting crashes on Windows, the most useful thing you can provide is a "dump" file. This contains important information about why Mixxx crashed which will help the development team find a fix.

To take a crash dump, follow these instructions:

When Mixxx crashes, you'll see a dialog similar to the following:
Do not click "Close the program"!
Hit the keys "control", "alt", and "delete" on your keyboard at the same time and click "Start Task Manager" on the screen that follows.
1. .
Find mixxx.exe in the list of programs, right-click it and hit "Create Dump File".
The dump file will be located on your computer in %APPDATA%\..\Local\Temp\mixxx.dmp or similar.
1. Tip: You can copy/paste %APPDATA%\..\Local\Temp\ into the start menu search box to open this folder.
Upload mixxx.dmp (or whatever the file was called) to the bug report on the Mixxx bug reporting system on Launchpad.