Re: [Xenomai-help] Problem with pthread_cond_wait

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Soboljew, Patrick wrote:
> Hello all,
> 
> I have a strange problem concerning the posix skin of xenomai (Ver.
> 2.4.9.1). Whenever two or more threads call 'pthread_cond_wait' and I
> want to interrupt the program with SIGINT (CTRL-c) only the main thread
> and the first thread that called 'pthread_cond_wait' get the signal. The
> remaining threads are not interrupted so I have created some zombies
> here. I discovered this problem when I tried to debug some code with the
> ACE/TAO Framework which calls these functions in a similar way. The
> debugger also has problems to interrupt these threads.
> 
> The small code example illustrates what I did.
> 
> Has anyone an idea what exactly causes this problem?

I believe the problem is that the other threads are blocked on the mutex
relocking by pthread_cond_wait. I believe this issue has just been
solved in 2.5 by the rework of pthread_cond_wait. I need to check with
your test program.

Getting the current situation to work implies handling the SIGINT (or
SIGTERM) by cancelling all threads. Then in each thread doing a
pthread_cond_wait registers a cleanup handler (pthread_cleanup_push)
that releases the mutex.

If I am right, I will check if it is possible to backport the
pthread_cond_wait rework without breaking the ABI.

-- 
                                          Gilles