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Electrolysis/Debugging: Difference between revisions
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('''TODO''') Apparently Windows has a magic debugger that works great with multiple processes. | ('''TODO''') Apparently Windows has a magic debugger that works great with multiple processes. | ||
= Linux = | |||
To debug only the parent process | == To debug only the parent process == | ||
M-x gdb, gdb --annotate 3 --args $objdir/dist/bin/firefox-bin -no-remote -P | |||
With GDB: just pass "-g" to your regular command line, ex: | |||
$objdir/dist/bin/firefox -no-remote -P JunkProfile -g -chrome chrome://global/content/test-ipc.xul | |||
With emacs gud-gdb: run | |||
M-x gdb, gdb --annotate 3 --args $objdir/dist/bin/firefox-bin -no-remote -P JunkProfile -chrome chrome://global/content/test-ipc.xul | |||
as you would for any other process. | as you would for any other process. | ||
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'''WARNING''': if the first time you run firefox after a rebuild is from within gdb, gdb will crash when firefox restarts itself. You can stop firefox from restarting itself by setting the NO_EM_RESTART environment variable. Or you can just run firefox once from the shell, outside of gdb. | '''WARNING''': if the first time you run firefox after a rebuild is from within gdb, gdb will crash when firefox restarts itself. You can stop firefox from restarting itself by setting the NO_EM_RESTART environment variable. Or you can just run firefox once from the shell, outside of gdb. | ||
To debug child processes only | == To debug child processes only == | ||
MOZ_DEBUG_CHILD_PROCESS=1 $objdir/dist/bin/firefox -no-remote -P | |||
Run firefox from the shell as | |||
MOZ_DEBUG_CHILD_PROCESS=1 $objdir/dist/bin/firefox -no-remote -P JunkProfile -chrome chrome://global/content/test-ipc.xul | |||
Each time a child process is launched, lines like this will be printed | Each time a child process is launched, lines like this will be printed | ||
CHILDCHILDCHILD | CHILDCHILDCHILD | ||
debug me @ [PID] | debug me @ [PID] | ||
To debug both the parent and children | ''(If you don't see this message, make sure you have set "dom.ipc.tabs.enabled" to "true", as described the [[Content Processes/Build|Build and Run Instructions]])'' | ||
You can attach to the newly launched child process with "gdb attach [PID]", or, for emacs gud-gdb, with M-x gdb, gdb --annotate 3 attach PID. | |||
== To debug both the parent and children == | |||
Make sure MOZ_DEBUG_CHILD_PROCESS is set in the environment you'll launch the parent from, and launch the parent process as above. (Unfortunately, as far as the author knows gud-gdb can't handle multiple gdb sessions ('''TODO: is that true?'''). So to debug child processes, you'll need to pull up a new shell for each and attach to them with good old "gdb attach PID".) | |||
== More Resources == | |||
Don't forget to check out the [https://developer.mozilla.org/en/Debugging_Mozilla_with_gdb main Mozilla gdb guide]. | Don't forget to check out the [https://developer.mozilla.org/en/Debugging_Mozilla_with_gdb main Mozilla gdb guide]. | ||