Random crash when using alsa output

Hi,

I have a random crash coming from alsa output, though I must confess I don't know if it may come from the application i'm building uppon VLC, or from VLC itself...

It seems to occurs as soon as I ingest audio datas (using the imem module) Here comes the backtrace :

[#0](https://code.videolan.org/videolan/vlc/-/issues/0)  0x00007ffff31e9035 in raise () from /lib/libc.so.6
[#1](https://code.videolan.org/videolan/vlc/-/issues/1)  0x00007ffff31ea460 in abort () from /lib/libc.so.6
[#2](https://code.videolan.org/videolan/vlc/-/issues/2)  0x00007ffff2f7294b in vlc_thread_fatal (action=0x7ffff2f9cf1e "locking semaphore", error=-1, function=0x7ffff2f9d173 "vlc_sem_wait", line=422,
    file=<value optimized out>) at ../../src/misc/pthread.c:124
[#3](https://code.videolan.org/videolan/vlc/-/issues/3)  0x00007fffebc87029 in ALSAThread (data=<value optimized out>) at ../../../modules/audio_output/alsa.c:761
[#4](https://code.videolan.org/videolan/vlc/-/issues/4)  0x00007ffff3cbb81a in start_thread () from /lib/libpthread.so.0
[#5](https://code.videolan.org/videolan/vlc/-/issues/5)  0x00007ffff3285c7d in clone () from /lib/libc.so.6
[#6](https://code.videolan.org/videolan/vlc/-/issues/6)  0x0000000000000000 in ?? ()

And the output :

[New Thread 0x7fffd503d710 (LWP 23447)]
LibVLC fatal error locking semaphore (-1) in thread 23447 at ../../src/misc/pthread.c:422 in vlc_sem_wait
/usr/local/lib/libvlccore.so.4(+0xa5873)[0x7ffff2f72873]
/usr/local/lib/libvlccore.so.4(+0xa5919)[0x7ffff2f72919]
/usr/local/lib/vlc/audio_output/libalsa_plugin.so(+0x4029)[0x7fffebc87029]
/lib/libpthread.so.0(+0x681a)[0x7ffff3cbb81a]
/lib/libc.so.6(clone+0x6d)[0x7ffff3285c7d]
 Error message: Unknown error 18446744073709551615

Regards,

added Component::Core: Audio output Severity::normal Type::bug Version::master git + 1 deleted label

changed milestone to %Bugs paradize

changed the description

assigned to @Courmisch and unassigned @MigrationBot

Unfortunately, the sem_wait() implementation was buggy so the provided debug is incorrect. Please retry with a newer version.

added Status::needs more info label

closed