Subj : Re: pthreads: cancelling thread blocked on berkeley socket accept()
To   : comp.programming.threads
From : David Schwartz
Date : Mon Sep 19 2005 08:35 pm


"David Hopwood" <david.nospam.hopwood@blueyonder.co.uk> wrote in message 
news:hMHXe.598$WV1.130@fe2.news.blueyonder.co.uk...

> David Schwartz wrote:

>> "David Hopwood" <david.nospam.hopwood@blueyonder.co.uk> wrote:

>>>You should set a shared 'shouldExit' flag and close() the socket from the
>>>main thread. The listening thread will get an error from the accept(), 
>>>and
>>>can then exit when it sees that 'shouldExit' is set.

>>     Note that this is a very dangerous thing to do and should only be 
>> done
>> as part of a shutdown process. It can cause terrible corruption.

> Only if the file descriptor has been reused.

    Something over which you have no control.

> Otherwise the accept() just
> gets an EBADF and the thread exits anyway. In shutdown code, you're 
> presumably
> not opening any new file descriptors.

    Suppose some library has a license checked out from a license server. On 
shutdown it may need to release that license. Suppose this program is 
registered as available in a central tracking server and on shutdown goes to 
unregister.

> OTOH, I agree that using shutdown() is better.

    Definitely.

    DS

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