'Twas brillig, and Myriam Schweingruber at 20/08/10 15:32 did gyre and
gimble:
> it would really be nice if these bugs could be solved, as they are
> reported on a nearly daily basis, making them real show stoppers:
> 
> 
> * https://bugs.kde.org/show_bug.cgi?id=196320 xine backend, has not
> less than 128 duplicates! See also comment #60 with a serious hint on
> how to solve that problem.
> 
> * https://bugs.kde.org/show_bug.cgi?id=207579 xine backend, has 91
> duplicates and makes listening to CDs almost impossible.
> 
> * https://bugs.kde.org/show_bug.cgi?id=232068 gstreamer backend, 63
> duplicates, seems to have some relation to Pulseaudio

For reference, I think I'm making some progress here on this one (at
last - I'm glad it's not the most reported bug :D

I think the problem is actually not specifically related to PA but it's
certainly the trigger case. So far I believe the problem is related to
thread-safety in alsa lib. The Phonon platform plugin does some alsa-lib
foo which in turn causes the gst backend to explode when closing the pcm
definition for pulseaudio (the alsa->pulse plugin). I suspect that any
ioplug plugin could cause this, but haven't tested this for sure.

I found a reliable way to reproduce the problem on a couple machines,
but it didn't happen on a third. The ones I could reproduce it reliably
on (every time) were multi-core systems (four and two cores, running
4.4.3 and 4.5 respectively). The one I could not reproduce on was single
core. This goes some way to reassuring me that it's a thread related issue.


I have a patch[1] for kdebase/runtime that removes calls to an alsa-lib
function that I believe is redundant and which is to blame of the
issues, but am following this up with Vir and alsa-devel to be sure.

If all goes well, I'll commit the patch in the near future.

Col

1.
http://svn.mandriva.com/cgi-bin/viewvc.cgi/packages/cooker/kdebase4-runtime/current/SOURCES/kdebase-runtime-4.5-alsa-global-config.patch?view=markup


-- 

Colin Guthrie
gmane(at)colin.guthr.ie
http://colin.guthr.ie/

Day Job:
  Tribalogic Limited [http://www.tribalogic.net/]
Open Source:
  Mandriva Linux Contributor [http://www.mandriva.com/]
  PulseAudio Hacker [http://www.pulseaudio.org/]
  Trac Hacker [http://trac.edgewall.org/]
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