Re: Bug when exiting the RTP send/receive thread

Do you think it is a defect in the core implementation of pthread_exit() 
itself?  That ThreadImpl should never call it?  You are correct that 
with a simple return, it will fall out.  One possibility would be to 
have a setjump/longjump in the trampoline function itself, and then have 
a Thread "::exit" method which always longjump back to the ThreadImpl 
function, and have that then just return for those cases where a thread 
"exit" at a deeper routine needs to be forced....

Werner Dittmann wrote:
> during some tests using GNU ccRTP on a cygwin system installed on a
> Windows XP SP2 I discovered some problems with the way ccRTP handles
> threads. This also together with the implementation of Thread in the
> common c++ library.
> 
> Ths usual way to stop a RTPSession is to delete the RTPSession
> object. The destructor of RTPSession then shuts down the RTP thread:
> 
> ~SingleThreadRTPSession()
> {
>     if (isRunning()) {
>         disableStack(); Thread::join();
>     }
> }
> 
> Note: the destructor runs in the thread that calls delete.
> 
> The "run()" method of RTPSession dutifully checks the "isActive" flag
> and exits the send/receive loop. After sending the BYE it calls
> Thread::exit():
> 
> ...
> 	}
> 	dispatchBYE("GNU ccRTP stack finishing.");
>         Thread::exit();
> ...
> 
> Note: The above is called by the RTP send/receive thread.
> 
> At least in the said cygwin environment calling Thread::exit() is evil
> :-) . The Thread::exit() just performs a pthread_exit() which
> immediatly stops (at least in cygwin) the RTP send/receive
> thread. Because of this "sudden death" the RTP send/receive thread is
> not able to do the necessary housekeeping that will wakeup the other
> thread waiting in join(). In other pthread implementations this might
> work (it works on my Linux boxes). However, after calling
> pthread_exit() the state and the thread's local variables are
> undefined according to the pthread manual pages.
> 
> Porposal: remove the "Thread::exit()" and let the run() just
> "return". This returns to the trampolin function
> ThreadImpl::ThreadExecHandler which will close the thread that kicks
> the join semaphore, then exits the thread. I've tested it an cygwin
> and Linux, no problems.
> 
> Remark: it is not necessary that ThreadImpl::ThreadExecHandler call
> pthread_exit() to terminate the thread, a simple return would be ok
> here.
> 
> Regards,
> Werner
> 
> 
> _______________________________________________
> Ccrtp-devel mailing list
> [email protected]
> http://lists.gnu.org/mailman/listinfo/ccrtp-devel

_______________________________________________
Ccrtp-devel mailing list
[email protected]
http://lists.gnu.org/mailman/listinfo/ccrtp-devel

begin:vcard
fn:David Sugar
n:Sugar;David
org:GNU Telephony
email;internet:[email protected]
tel;work:+1 201 215 2609
url:http://www.gnutelephony.org
version:2.1
end:vcard