[alsa-devel] pcm write from posix threads
Brian Rhodes
bgr at acdstar.com
Wed Aug 20 10:39:18 CEST 2008
Thanks for reassuring me that there isn't some sort of incompatibility
with alsa lib and threading. I am not able to reproduce the issue on an
x86 system and it only seems to happen when built with a specific
toolchain for ARM.
Takashi Iwai wrote:
> At Tue, 19 Aug 2008 17:24:06 -0500,
> Brian Rhodes wrote:
>
>> When calling snd_pcm_write* from a thread how do you safely cancel the
>> thread? I've tried masking the signals which are used in alsa lib, yet
>> I am getting a segfault on pthread_exit(). My thread is looping doing
>> the following.
>>
>> testcancel
>> snd_pcm_wait
>> snd_pcm_avail
>> snd_pcm_writei
>>
>> I am checking return values to handle those functions being woken up by
>> pthread cancel and attempting to exit. In testing the process it
>> performs fine until I start actually writing data. Once I write some
>> data, a pthread_exit will segfault. My cancellation routine is calling
>> snd_pcm_drop, then doing a cancel followed by join.
>>
>
> No, alsa-lib functions don't care threads in general.
> Some codes have uses pthread_mutex, but not in the PCM core code, at
> least.
>
> You need to handle and protect threads by yourself.
>
>
> Takashi
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>
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