Re: boost.threads [was RE: [boost] Re: sockets /network programming Requirements]

From: Scott McCaskill (scott_at_[hidden])
Date: 2001-08-02 17:57:26

> > Thanks, got it.  I've been perusing the source quite intently and
> so far I
> > really like what I see.  I also have a question.  I have an
> application that
> > creates several threads and I want the main thread to be able to
> find out if
> > any of the created threads have died.  It appears that I could do
> this using
> > boost::thread::try_join() on each of the created threads, but is
> there (or
> > will there be) a better way?  Currently, the app is using
> > WaitForMultipleObjects() to do this.
>
> The Wait* operations in Win32 threading are both extremely nice, and
> a major pain.  Boost.Threads doesn't directly support any concepts
> similar to WaitForMultipleObjects (other than
> thread_group::join_all).  However, it's not difficult to do what you
> want here using a condition variable, though this requires support
> from the threads which will have to notify_one/all() the condition.
>

Yes, I'm also considering this.  It will work as long as the thread exits by
some "normal" means, which it always should (i.e., by returning from the
thread function, not because something called
_endthreadex/pthread_exit/etc).  I just thought it would be a bit more
robust if I could also get asynchronous notification in all cases.

> > I realize that this is probably just an optimization, but it feels
> strange
> > to have to poll to find out if a thread has ended.
>
> Are you _trying_ to find out if a thread has ended, or waiting until
> any thread has ended?  In other words, is the wait a blocking
> operation?
>

Right now it checks (polls) periodically to see if any have ended.  I'm
considering what the implications would be if I changed it to wait (block)
until any thread ended.