Unity8 crashed right clicking on vlc [terminate called after throwing an instance of 'std::out_of_range' what(): map::at]

from unity8.log (it's pretty hard to read the log :( too much debug spam)

[2017-03-11:11:56:48.152] qtmir.surfaces: MirSurface[0x55ab6bf156b0,"vlc"]::setRequestedPosition(QPoint(199,194))
[2017-03-11:11:56:48.152] qtmir.surfaces: MirSurface[0x55ab6bf156b0,"vlc"]::requestState(restored)
terminate called after throwing an instance of 'std::out_of_range'
  what(): map::at
[2017-03-11:11:56:4

Alan recently said this was either fixed already (bug 1656727) or not relevant to U8 (bug 1668466). See also older bug 1497128.

Given we have four known bugs for menu-related things crashing the server in 'what(): map::at', and two of them still open, I feel we've possibly still missed the root cause here... Perhaps see: https://bugs.launchpad.net/mir/+bug/1668466/comments/5

dinamic: That "debug spam" has a fix on the way; bug 1664151.

Status changed to 'Confirmed' because the bug affects multiple users.

Another /possible/ cause of "'std::out_of_range' what(): map::at]" is bug 1667645. That would imply that vlc is crashing and the server dies in closing the session.

It would be good to get a log with MIR_SERVER_WINDOW_MANAGEMENT_TRACE=on as that ought to log the operation that propagates the exception.

Investigating this with miral-app: the server doesn't crash and nor does the client.

Which is suggestive of a QtMir issue. However, the server fails to shut down after this experiment which clearly can't be QtMir.

MIR_SERVER_WINDOW_MANAGEMENT_TRACE shows that miral-shell doesn't provoke "'std::out_of_range' what(): map::at]" - but that doesn't explain the failure to exit. We either have two problems or two symptoms of one underlying issue.

Finally, mir_demo_server doesn't crash and exits successfully. (The menus don't display correctly, they disappear as soon as they get focus. But that's another issue.)

I've split off the miral-shell "hang on exit" as lp:1673038 since it looks entirely separate to the Unity8 crash.

It *is* also possible to crash miral-shell this way - after numerous runs where it "merely" hung on exit I have a crash.

Correction to #14 - the miral-shell crash (and the hang on exit) seems to be entirely down to racy decorations code. Both the "tiling" window manage and miral-kiosk are entirely stable.

I *think* this is QtMir.

Don't know what's different in my system but here vlc won't launch. I can launch firefox though which displays the same bug (menus immediately disappearing) but it doesn't cause unity8 to crash.

I can now see something like this with miral-shell:

[terminal 1]
$ miral-shell

[terminal 2]
$ miral-xrun vlc

Right click a few times in rapid succession.

Expect: nothing bad
Actual: [terminal 1] Aborted (core dumped)

Is the client crashing? See bug 1668466

Actually, I seem to be seeing a new bug: lp:1704949

We'll never see a fix in Unity8, so we'll never know if it also requires any change to Mir.

As we can not reproduce the problem in any current project: I declare this bug invalid.