[pulseaudio-discuss] pulseaudio daemon not responging

[Stefan Stefanov]

Can anyone explain me what is wrong with libpthread-stub.so?

As I understand, sem_wait() works as intended according to the source code:
static int __sem_wait_stub(sem_t *_sem)
{
    unsigned int *sem = (unsigned int *) _sem;
    if (!*sem) {
         /* Not available, simulate a blocking sem_wait */
         pause();
         errno = EINTR;
         return -1;
    }
    *sem--;
    return 0;
}

If the semaphore is available, sem_wait decrements the semaphore value
and returns to the caller.
If the semaphore is unavailable, sem_wait suspends execution of the
calling thread by call of pause().

Obviously in our case semaphor is unavailable (null), thus it blocks.



2012/11/22 Stefan Stefanov <selectany at gmail.com>:
>>http://thread.gmane.org/gmane.comp.audio.pulseaudio.general/11000
> Exactly the same problem as mine.
>
> 1. Build of pulseaudio failed without libpthread-stubs.so with "no
> such file ..."
> 2. I noticed that in crux linux, sem_wait() resides in
> libpthread_stubs.so, and it is found through call to libpthread.so,
> but in my arch linux box there are no libpthread_stubs.so at all. So,
> I think that sem_wait() (in my arch linux box) resides in
> libpthread.so.
>
> Is it possible to upgrate libpthread.so? Which package I must upgrade?
> I cannot just delete libpthread-stubs.so.
>
> Finally, I see something strange when run ./configure of
> libpthread-stubs-0.2 source code (which is currently in use of my
> distro).
> Here is output snippet after running ./configure:
> ....
> ....
> checking for pthread_cond_wait... yes
> checking for pthread_cond_signal... yes
> checking for pthread_cond_broadcast... yes
> checking for pthread_equal... yes
> checking for sem_init... no
> checking for sem_destroy... no
> checking for sem_wait... no  -> HERE!!!
> checking for sem_trywait... no
> ....
> ...
>
>
> 2012/11/22 Tanu Kaskinen <tanuk at iki.fi>:
>> On Thu, 2012-11-22 at 15:15 +0200, Stefan Stefanov wrote:
>>> #2  0xb7b1f665 in sem_wait () from /usr/lib/libpthread-stubs.so.0
>>
>> I think libpthread-stubs.so.0 isn't a very good implementation for
>> sem_wait()...
>>
>> I don't have any straightforward advice for what to do, but maybe you'll
>> find this thread useful:
>> http://thread.gmane.org/gmane.comp.audio.pulseaudio.general/11000
>>
>> --
>> Tanu
>>