Re: [fluid-dev] Possible freeze in delete_fluid_alsa_audio_driver()

[Pedro Lopez-Cabanillas]

On Tuesday 02 November 2010, Sven Meier wrote:
> Hi all,
> 
> I'm experiencing a strange freeze in delete_fluid_alsa_audio_driver():
> 
> 0x9da58ae5    fluid_thread_join + 0x1d
> 0x9da4d388    delete_fluid_alsa_audio_driver + 0x47
> 0x9da81c74    delete_fluid_audio_driver + 0x59
> 
> The attempt to join the (synthesizer?) thread never returns (line #332):
> 
>    dev->cont = 0;
>    if (dev->thread)
>      fluid_thread_join (dev->thread); /* never returns */
> 
> To trigger this issue the following prerequisites have to be met:
> - Jack is running
> - a fluidsynth instance is created with "audio.driver" explicitely set 
> to "alsa".
> - finally the fluidsynth instance is deleted.
> 
> I've just double checked by starting fluidsynth from the command line 
> and this seems to expose the same issue:
> 
> $ fluidsynth -a alsa
> FluidSynth version 1.1.3
> ....
> fluidsynth: debug: Using 'alsa' audio driver
> fluidsynth: debug: Using 'alsa_seq' midi driver
> Type 'help' for help topics.
> ....
>  > quit
> cheers!
> <nothing happens after cheers>
> 
> BTW I'm using the latest fluidsynth from SVN.
> 
> Any ideas?

I can confirm the freeze when PulseAudio is also running. Jack typically 
doesn't use PulseAudio. When I run fluidsynth using an ALSA hw device the 
freeze doesn't happen. For instance:

$ fluidsynth -a alsa -o audio.alsa.device=hw:0,0

Note that many cheap audio interfaces don't allow two programs opening the 
same hw device at the same time.

When you don't tell an explicit device, ALSA uses "default" which is routed to 
the PulseAudio plugin if you have it installed. You can verify this in your 
"/etc/asound-pulse.conf" or "/etc/asound.conf". To defeat this setting for 
your own account, you can create a file at your $HOME named ".asoundrc" with a 
content like this one:

pcm.!default {
    type hw
    card 0
}

ctl.!default {
    type hw
    card 0
}

Anyway, the freeze requires more investigation before deciding if it is a bug 
in ALSA, PulseAudio, or FluidSynth.

Regards,
Pedro