Frequent different crashes when closing on Mac OS X

[follower]

As it was unclear whether #2633 is supposed to be reserved for a specific instance of a crash at close, I thought I'd create a new issue since it appears there may be multiple crash-at-close causes.

I get crashes on close around 75% of the time on OS X 10.8.5 / Qt 5.5.1 / LMMS 1.2.0-rc2.x master but they don't appear to prevent the settings from being saved or have any other negative effect other than inconvenience.

I wanted to get an insight into the common aspects of the crashes so wrote crashlytics.py as a starting point for summarising the ~/Library/Logs/DiagnosticReports/lmms_*.crash files (it's slightly but not entirely re-inventing the wheel): crashlytics.py

I've attached two summaries ("A" has 1 line of backtrace, "B" has 5 lines of backtrace) that are the current output of the script:

• lmms-crash-report-summary-20170220A.txt
• lmms-crash-report-summary-20170220B.txt

Summary of the summaries:

Total reports processed:  20
EXC_CRASH (SIGABRT) | Occurrences:  5
EXC_BAD_ACCESS (SIGSEGV) | Occurrences:  13
EXC_BAD_ACCESS (SIGBUS) | Occurrences:  2

Ideally the script would help identify common backtraces more than it does at the moment but it's at least a helpful way to get a rough summary.

(QObjectPrivate::deleteChildren() does seem to occur frequently.)

Feel free to close this issue until more details get added by me or someone else.

(I also installed and ran Valgrind which highlighted some issues but I've not investigated them because as usual I'm trying to do too many things at once. :) )

[zonkmachine]

All I can tell from those crash reports is that it looks like it's Qt related.

I get crashes on close around 75% of the time on OS X 10.8.5 / Qt 5.5.1 / LMMS 1.2.0-rc2.x master

Do you know if this is a recent development? If it happens as much as 75% of the time you could try a bisect to see if there is one specific commit that relates to the crashes.

Which theme do you use?

[follower]

LMMS has frequently crashed on close since I first started using it (which I think was with LMMS 1.1.3? (I just confirmed I got crash on exit 1 out of maybe 5 times with 1.1.3 now)), so it's not a new development (which was why originally I assumed #2633 covered the issue).

The cause and/or frequency might have changed over time but I couldn't quantify that currently.

I use both classic & default theme--haven't noticed it being related to the theme but might've missed something.

I assume it's related to incorrect memory use but without further data/investigation it's hard to think we'd make much progress. I can provide full traces for each of the above crashes if that might help. I've also not been able to notice what reliably reproduces any particular crash either.

Just FYI currently I'm not terribly invested in finding the underlying cause with other things to work on but thought that a summary of the crash data might show some insight so thought I'd at least contribute it.

[follower]

A couple of additional MIDI-related example crash logs in my notes here: http://www.labradoc.com/i/follower/p/notes-lmms#20171008. (Seem to be different to issue fixed by #3655.)

[follower]

Note to self: try out aboutToQuit() approach mentioned here.