[Thread-SIG] RE: tstate invalid crash with threads
scothrel at cisco.com
Wed Jun 9 18:40:03 CEST 1999
I can confirm that we were seeing similar behavior under a highly threaded,
highly stressed situation. We backed off on the number of threads and
slowed things down as a workaround also. We couldn't trace it down to
Python, as we have a Java, C, Python mix that has too many suspects.
Cisco Systems, Inc.
----- Original Message -----
From: Tim Peters <tim_one at email.msn.com>
To: Ray Loyzaga <ray at commsecure.com.au>; Guido van Rossum
<guido at python.org>; Thread-SIG <thread-sig at python.org>
Cc: <python-list at python.org>
Sent: Wednesday, June 09, 1999 12:18 AM
Subject: [Thread-SIG] RE: tstate invalid crash with threads
> Followups to the Thread-SIG, please.
> [Ray Loyzaga]
> > I have been playing with a multithreaded tcp based server for a while,
> > and during some serious stress testing continually hit a problem
> > involving the interpreter crashing with "Fatal Python error:
> > PyThreadState_Delete: invalid tstate".
> > ...
> > It appears to be a subtle race in PyThreadState_Delete ....
> > interestingly, if I uncomment the small sleep in "handle" in the server,
> > ie. make the server slower, it seems to work for ever ... 4m
> > before I gave up. I think the problem only comes if you are creating and
> > destroying threads quickly in parallel.
> PyThreadState_Delete is called from very few places, and one of them
> me as suspicious: at the end of threadmodule.c's t_bootstrap, we have:
> The suspicious thing here is that PyEval_ReleaseThread releases the global
> interpreter lock, so nothing is serializing calls to PyThreadState_Delete
> made from the following line. PyThreadState_Delete in turn does no
> of its own either, but mutates a shared list.
> If this isn't plain wrong, it's certainly not plain right <wink>. Matches
> your symptoms, too (very rare blowups during high rates of thread death).
> Guido? I haven't been able to provoke Ray's problem under Win95, but the
> above just doesn't smell right.
> meanings!-ly y'rs - tim
> Thread-SIG maillist - Thread-SIG at python.org
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