Re: Thread: memory leak when using not detached thread?

[David Sugar]

A thread cannot delete it's own context or join itself.  To make a thread
that is a self running object that self-deletes, one has to detach the
thread.  However, there is very definately a known bug in at least some
glibc releases that when a detached thread exits, it will not clean up
it's stack frame allocations because that code only existed in the 
pthread_join implimentation, and, of course, one cannot self join...

On Mon, 9 Dec 2002, Gernot Hillier wrote:

> --[PinePGP]--------------------------------------------------[begin]--
> Hi!
> 
> I'm no pthread guru, so perhaps I've misunderstood something. Please excuse
> this ;-)
> 
> I narrowed my problem down to a very small test application. See attached
> test.cpp file.
> 
> This program produces a memory leak - i.e. a finishing thread doesn't free its
> resources.
> 
> I had a small look on the sources and the problem seems to be in
> Thread::terminate():
> 
>         if(pthread_self() != priv->_tid)
>         {
>                 printf("grbml\n");
>                 // in suspend thread cannot be cancelled or signaled
>                 // ??? rigth
>                 // ccxx_resume(priv->_tid);
> 
>                 // assure thread has ran before we try to cancel...
>                 if(_start)
>                         _start->post();
> 
>                 pthread_cancel(priv->_tid);
>                 pthread_join(priv->_tid,NULL);
>         }
> 
> This doesn't get called as pthread_self() seems to be the same thread which
> deletes this. So pthread_join isn't called and the resources aren't freed.
> 
> Now I thought Thread::final() won't run in the same thread context as my new
> thread? So why doesn't this work?
> 
> Do I have to use Thread::detach() instead of Thread::start() when I want to
> "delete this"?
> 
> Could you elaborate on the cited glibc bug mentioned in the Thread::detach()
> docu? I asked a glibc developer and he told me that it's my fault if I don't
> run pthread_join - no glibc bug.
> 
> I've seeked the archives a  little bit but found no mail responding my
> question. Sorry if this is a FAQ.
> 
> --
> Ciao,
> 
> Gernot
> "Der Horizont vieler Menschen ist ein Kreis mit Radius Null - und das nennen
> sie ihren Standpunkt." (A. Einstein)
> --[PinePGP]-----------------------------------------------------------
> gpg: Warning: using insecure memory!
> gpg: Signature made Mon 09 Dec 2002 05:12:42 AM EST using DSA key ID 619E49E2
> gpg: Can't check signature: public key not found
> PinePGP: Encryption backend encountered error.
> --[PinePGP]----------------------------------------------------[end]--
>