Re: [Denemo-devel] denemo causing session crash

[Richard Shann]

On Sun, 2018-04-08 at 07:15 -0400, Bric wrote:
> > On April 7, 2018 at 9:58 PM Bric <address@hidden> wrote: 
> > 
> > I occasionally experience a denemo crash on my Ubuntu 16.04 LTS
> > which crashes my entire session, ending with the Ubuntu user login
> > screen.
> > This has happened several times, when I am refreshing the "Typeset
> > Music" window, after some particular change. And today it happened
> > again after the pop-up dialog "Restart Subsystem?", to which I
> > answered "OK" and then got the crash.  And then another crash
> > logout when I changed settings - unchecked "Spill notes to next
> > measure" and (i believe) clicked to refresh the Typeset Window.
> > After that it crashed again, when I (re)started denemo (after I
> > deleted the auto-saved document), before any user activity,
> > 
> > After that I logged back in, and it has run without crashing.
> > 
> > It might be tricky to capturing the crash/debug messages here (not
> > sure), since I get totally logged out, immediately (I could be
> > wrong)
> > 
> > Just thought I'd report it finally.  This has been rare, such that
> > I kept ignoring it.
> > 
> > I am using Gnome metacity classic
> > 
> > Linux **** 4.4.0-112-generic #135-Ubuntu SMP Fri Jan 19 11:48:36
> > UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
> 
>  Hmm... This install/build of Denemo is becoming unusable for me.
> 
> Just crashed again, when I started it and then invoked the playback
> window.   I was trying to fix my lack of audio playback - it suddenly
> went silent in all windows that should produce playback sound.   When
> I press "play" in the editor there are no errors, and the cursor is
> moving, as it normally does during playback, but there is no sound.
> 
> I am suspecting the crashes to be related to the audio component... I
> used to use jack audio on other Ubuntu setups, but have not been
> lately - using pulse.  I remember crashes years ago, related to the
> wrong audio configuration
> 
> Needless to say (but i'm saying it nonetheless):  the x session crash
> is devastatingly disruptive; i don't remember experiencing anything
> like that before... an app bringing down the whole session.

The only similar thing I have seen is some failure between Gtk and X
when re-sizing the Print View - the program hangs with Gtk waiting for
X to respond. I've also got the X-interaction stuck when telling the
debugger to stop the program at a point where a menu has just been
popped up - the menu has grabbed the interaction and the only thing
that works is Ctrl-Alt-Fn5 which gives a login prompt. I login and then
 kill off the denemo process at the command line and then use Ctrl-Alt-
Fn7 to go back to my X-session.

You may find it a good practice to *always* run Denemo from the gdb
prompt - it runs just as well but if it crashes gdb will be able to
tell you where the crash happened.
> 
> Also:  My gnome session gives me some errors when I first log into
> Ubuntu, but i haven't had any "fatalities" until this one, so i've
> been ignoring those.  Perhaps it's time to address these - could be
> some weird combination of that plus denemo specifics.

The re-start of the Audio subsystem can certainly cause a crash, that's
why the dialog asks you before trying it. I don't have any real
suspicion that the problem lies with Denemo, unknown MIDI hardware is
notoriously difficult to interact with safely, the manufacturer may or
may not have got it right. Currently my machine randomly switches
between line out and headphones, but I'm pretty sure that is a hardware
fault that has developed. It happens a lot after resuming a session,
but settles down for long periods after a while.

Richard