Re: [Boost-users] boost::thread::join causes assertion (pthreads)

From: Ben Hutchings (ben.hutchings_at_[hidden])
Date: 2005-03-21 09:43:39

Thorsten Froehlich wrote:
> Hi,
> 
> I noticed that when using thread::join and the thread has already 
> completed,

I'm not sure whether you mean that the thread has exited or that it has 
also been joined.

 > at least on Mac OS X using pthreads, pthread_join returns
> EINVAL, thus triggering the assertion res == 0.  Is this intentional or 
> a bug?

Which part of this behaviour are you questioning?

The reasons why pthread_join may fail all represent bugs rather than 
unpredictable errors, hence the assertion.  Joining a thread makes the 
thread object an empty shell which has no further use.    Detaching a 
thread also makes it non-joinable and makes the thread object almost 
useless.  If your program attempts to join a non-joinable thread, that's 
the bug.  Otherwise, it is conceivable that you have found a bug in 
MacOS X or in Boost.Threads, but I'd be surprised.

Ben.