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Re: PTHREAD_CANCELED

On Feb 27, 2004, at 4:35 AM, Daniel Oberhoff wrote:

since this must have missed attention in the last mail, is there any meaning in the fact that PTHREAD_CANCELED is not defined in pthread? the man page still states it as the indicator of cancellation of the thread after pthread_cancel ().

pthread cancellation isn't really implemented in Darwin. Check out pthread_cancel() in <http://cvs.opendarwin.org/index.cgi/Libc/pthreads/pthread.c? rev=1.1.1.1&content-type=text/x-cvsweb-markup&cvsroot=apple> - it just sets a flag; it doesn't deliver a signal or anything, as would be necessary to immediately wake it from a blocking call or during async cancellation.

(I did see a message in the archives of this list that they have a more complete implementation of cancellation but are holding off because many frameworks are not cancel-safe. So it exists, but it's not available, and with good reason if you're using those frameworks...)

Also, as obviously lacking as the Darwin implementation is, I've found it doesn't really work well anywhere else, either. I've got a bunch of tests at <http://www.slamb.org/svn/repos/projects/cancellation_tests/ index.html>, and my conclusion is that cancellation is not worth using and won't be for some time.

So, I'm afraid you'll need to find another way of doing what you want. Sorry.

Scott
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References: 
 >PTHREAD_CANCELED (From: Daniel Oberhoff <email@hidden>)



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