Re: Waiting for threads

[Richard Frith-Macdonald]

On Tuesday, July 22, 2003, at 03:39 PM, Raffael Herzog wrote:

> Hi,
>
> Situation:
>
> - An object (a) starts a new thread when initialized
> - This object a is also a factory for other objects (b), each of which 
> starts its own thread, too
> - When object a receives a dealloc message, it sets its status 
> accordingly causing all those threads to exit ASAP
>
> The problem is this "ASAP". I don't know exactly *when* a thread 
> actually exited, but I need to make sure that all dependent threads 
> have exited before the object that started them gets deallocated. What 
> I'm looking for is something like Thread#join() in Java:
>
> Thread myThread = new Thread(myRunnable);
> myThread.start();
> // do something...
> myThread.requestStop(); // ask the detached thread to exit
> myThread.join(); // wait until the thread actually exited
>
> How can this be achieved with GNUstep?

You can register as an observer of NSThreadWillExitNotification to see 
when threads exit (never tried it).

If you need to block until the thread ends, you could have the thread 
obtain a lock on startup, and release it in the notification observer, 
then have your main thread block trying to obtain the lock until the 
exiting thread releases it.