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From: Richard.Draves@CS.CMU.EDU
Newsgroups: comp.os.mach
Subject: Re: notification of thread death
Message-ID: <8ZqaNoK00hYPEpsEdz@cs.cmu.edu>
Date: 15 Feb 90 08:21:08 GMT
References: <371@kgw2.bwi.WEC.COM>
Sender: rpd@M.GP.CS.CMU.EDU
Distribution: usa
Organization: Carnegie Mellon, Pittsburgh, PA
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In-Reply-To: <371@kgw2.bwi.WEC.COM>

You are seeing two different problems.

First, when a cthread exits, the underlying Mach thread is not
terminated.  It is left lying around, and will be reused for a new
cthread.  Because the underlying Mach thread isn't killed, the thread's
kernel port isn't deallocated, and you don't see notification messages.

Second, when a Mach thread is terminated, there is a special hack to
keep the task it is in from getting a notification about the death of
the thread's kernel port.  Other tasks that have send rights for the
port do get notification messages, as expected.  This speeds up task
termination, because it saves generating a bunch of notification
messages (that will never get received) for all the threads.  But it is
a hack, and I can't defend it very enthusiastically.

In any case, I don't think it is a good idea to kill a thread that the
cthreads library thinks it is using.

Perhaps you could just have your cthread send its own notification
messages before it exits?

Rich