Simple example of threading
gmcm at hypernet.com
Thu Feb 24 17:22:33 CET 2000
Dirk Vleugels wrote:
> ... Under posix_threads there is pthread_cancel. This call
> is used to 'cancel' misbehaving threads (blocking on certain system
> calls (see doc)). The thread may ignore cancel requests, but this is
> under user control.
> Sadly, pthread_cancel is missing in python, dunno why.
For the same reason that Java has deprecated it. In almost all
implementations, you can't interrupt a blocking call; all you
can do is queue up a "cancel" that the blocked thread will get
after (if ever) it returns from the blocking call. That's easy to do
at the application level.
"Killing" a thread is very dangerous. Most OSes implement
threads as "lightweight processes". The fat that has been
trimmed is all the automatic clean-up. So resources (in
particular, semaphores and other locks) that the thread has a
claim on will not be released, leaving the process in an
Java has also added timeouts to socket calls to help deal with
this. It's a safe bet that that's actually select with a timeout,
followed by the socket call. So maybe in a couple years, Java
will let you multiplex multiple sockets in one thread, as God
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