Re: [Alsa-xmms-user] dmix plugin / will it work one day?

[Matthieu Sozeau]

On Saturday 14 June 2003 20:56, Steve Leung wrote:
> On Sat, 14 Jun 2003, Matthieu Sozeau wrote:
> > His card has the same behavior (hangs on stop), but i've found something
> > interesting: when you switch songs (it closes and reopens the device each
> > time), it works most of the time. Can you try that ?
>
> Yes, this seems to work most of the time.  When I wrote the test
> program, I noticed that adding the sleep() call made the deadlocking
> more consistent.  Forgot to mention that, sorry.. :)
No problem :)

> ...
> However, I've discovered something interesting:  alsa-xmms seems to
> work fine as long as another program keeps the dmix sound device open.
>
> I discovered this by running aplay in the background, then starting
> alsa-xmms.  As long as aplay kept the sound device busy, I was able to
> stop and start songs whenever I wished, and alsa-xmms never hung.
>
> I've even started two xmms instances (both using dmix) and verified
> the same result.  I can start and stop songs in either instance so
> long as the other instance is busy playing something.
>
> If I run a program that simply calls snd_pcm_open, then sleeps
> forever, then I do not see any hanging in xmms.  This could be
> considered yet another (bad) workaround. :)
>
> The reason why switching songs works most of the time may be because
> the time between closing and opening the device is so short.  It's
> possible that dmix has some kind of 'keepalive' feature that prevents
> deadlock.  I suppose that xmms could also be using the same thread to
> close and reopen the sound device, which may also prevent hanging.

It seems to be a deadlock problem with dmix and it's IPC part
gdb says it stops in open() from libc and valgrind says server_job in 
libasound has some problems too.

I can't find your message in the alsa-user archives, what's the subject ?
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