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Bug 721943 - easytag hangs during startup
easytag hangs during startup
Status: RESOLVED FIXED
Product: easytag
Classification: Other
Component: general
2.1.x
Other Linux
: Normal normal
: 2.1
Assigned To: EasyTAG maintainer(s)
EasyTAG maintainer(s)
Depends on:
Blocks:
 
 
Reported: 2014-01-10 15:39 UTC by Andreas Schneider
Modified: 2014-01-21 20:13 UTC
See Also:
GNOME target: ---
GNOME version: ---

Attachments
strace of easytag startup (226.53 KB, text/plain)
2014-01-10 15:41 UTC, Andreas Schneider 		Details

Description Andreas Schneider 2014-01-10 15:39:59 UTC 
If I try to start easytag most of the time it hangs during the startup. Most of the time I only get it running if I get all of my 6 CPU's busy and slow down the startup.

It seems to be a race condition. I can't even call 'easytag --help' it hangs forever ...
Comment 1 Andreas Schneider 2014-01-10 15:40:59 UTC 
I use easytag-2.1.8
Comment 2 Andreas Schneider 2014-01-10 15:41:34 UTC 
Created attachment 265936 [details]
strace of easytag startup
Comment 3 David King 2014-01-10 17:28:18 UTC 
Thanks for the bug report, and especially the strace output. The symptoms and trace makes me think that it might be related to qtcurve. I remember reading a bug report where updating qtcurve fixed the problem:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=711738
https://bugs.kde.org/show_bug.cgi?id=318891

Can you check that you have a version of qtcurve that has the patch in the Debian bug, or that you are using a recent version of glib that does not have the problem (I think that 2.36.2 should be fine)?
Comment 4 Andreas Schneider 2014-01-11 18:29:01 UTC 
Yes, you are right. The problem is the use of popen and that something registers a SIGCHLD handler which doesn't work with popen().

https://github.com/QtCurve/qtcurve/issues/41
Comment 5 David King 2014-01-11 19:11:13 UTC 
Good to know, thanks.
Comment 6 Andreas Schneider 2014-01-21 15:18:57 UTC 
Well, it looks like easytag setups up a SIGCHILD handler for rccexternal. So if a library forks and exec's another process it hangs forever.

If I send a TERM signal to the rccexternal process easytag starts.
Comment 7 David King 2014-01-21 20:13:12 UTC 
I removed the signal handlers in commit b698dad4c31ffc702121cc06200ff1a0e1e89864 on master. In the two following commits I switched the two uses of fork() in EasyTAG to instead use g_spawn_async() and g_child_add_watch() followed by g_child_watch_add() and g_spawn_close_pid().