[nptl] Re: [offtopic] NPTL question

["Loic Domaigne" <loic-dev@gmx.net>]

Hello Bharath, 

> Sorry to diverge from the main purpose of this mailing list. I have a
> question, which basically could question my understanding of POSIX
> threads in general. If this is the wrong mailing list would really
> appreciate if you could direct me to a better list where I could post my
> question. 

If you have question about POSIX threads in general, the appropriate 
newsgroup is comp.programming.threads. 


> Question is as follows:
> I have signal say SIGRTMIN which I have blocked in all the threads that
> I create. I do this by using sigprocmask before I fire my threads. I
> have a thread which handles SIGRTMIN without explicitly using a
> sigaction. Since I blocked the signal SIGRTMIN, I assume that it would
> be in the pending queue for delivery. I use sigwaitinfo to dequeue the
> signal in the appropriate thread by looping infinitely. I find that I am
> unable to dequeue the signal inside my thread, but I am able to dequeue
> the same signal in the main process that fires off all the threads. Is
> this the behavior of POSIX threads or my understanding is correct and
> this is a bug in the implementation of NPTL or is a bug in the Linux
> kernel which causes this to happen.

Perhaps this is not the reason of your problem, but I see at least one 
mistake from a POSIX viewpoint. The XSH sigprocmask() is only well defined 
for single-threaded process. For multi-threaded process, you should use
pthread_sigmask() instead. 

Let see if that correct your problem. If not, we shall investigate your 
problem further ( if you are sending SIGRTMIN to your process, your
expectations are correct and the behavior you are describing seems to 
indicate a bug). 


HTH,
Loic. 

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