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Killing a thread

Donn Cave donn at u.washington.edu
Mon Jul 19 13:18:27 EDT 1999 
catlee at my-deja.com writes:
| I'm writing a progrma where some user code is executed in a restricted
| environment running in a separate thread.  Now, if the user is
| malicious, s/he can just put 'while 1: 1+1'.  I'd like to be able to
| recover from this.  Is there any way I can kill the thread that is stuck
| in the infinite loop?

Python's thread support is evolving.  As a previous followup points out,
you shouldn't kill threads, and I guess that's fair enough - in terms
of normal program design, one should look for other ways to manage
threads.

But in default of any alternative, I suspect sometimes we have to violate
this commandment, and I think one of these days Python will provide the
tools to do what you have to do, not just what you want to do.  At the
moment though, it looks to me like you have to go outside Python's thread
support.  For example on BeOS (happens to be the only OS where I've played
with threads), I find I can kill a thread with os.kill(bad_thread_id, 21)
(SIGKILLTHR == 21)  The thread doesn't clean up normally, but it stops.

	Donn Cave, University Computing Services, University of Washington
	donn at u.washington.edu
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