[ python-Bugs-1010777 ] test_queue fails occasionally

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Bugs item #1010777, was opened at 2004-08-17 10:54
Message generated for change (Comment added) made by tim_one
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Category: Threads
Group: Python 2.4
Status: Open
Resolution: None
Priority: 5
Submitted By: Michael Hudson (mwh)
Assigned to: Tim Peters (tim_one)
Summary: test_queue fails occasionally

Initial Comment:
I guess this is some kind of race condition.  I see
test_queue fail about 5% of the time (judged by running
./python ../Lib/test/regrtest.py test_queue test_queue
test_queue test_queue ... with a couple of hundred
test_queue's, but I've seen it fail as part of a more
normal test run too).

It's always this failure:

test test_queue failed -- blocking function '<bound
method FailingQueue.put of
<test.test_queue.FailingQueue instance at 0x4041b184>>'
appeared not to block

and then, at least sometimes, you get this traceback:

Exception in thread Thread-3408:
Traceback (most recent call last):
  File
"/home/mwh/src/python/dist/src/Lib/threading.py", line
442, in __bootstrap
    self.run()
  File
"/home/mwh/src/python/dist/src/Lib/test/test_queue.py",
line 23, in run
    self.fn(*self.args)
  File "/home/mwh/src/python/dist/src/Lib/Queue.py",
line 129, in get
    item = self._get()
  File
"/home/mwh/src/python/dist/src/Lib/test/test_queue.py",
line 58, in _get
    return Queue.Queue._get(self)
AttributeError: 'NoneType' object has no attribute 'Queue'

somewhat later, usually while a subsequent test is running.

This is a debug build from CVS as of an hour or so back
on Redhat Linux 9 (so, in particular, with the NPTL
threading libray, not LinuxThreads).

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>Comment By: Tim Peters (tim_one)
Date: 2004-08-17 22:43

Message:
Logged In: YES 
user_id=31435

FYI, Guido and I first noticed that test_queue sometimes fails 
a few years ago.  It's apparently much more likely to fail on a 
non-Windows box, perhaps because Windows is happy to 
switch threads frequently.  I ran it for half an hour today on 
a WinXP box, and it didn't fail at all.  IIRC, it's not easy to fix -
- there are threads, and some of the coordination is done via 
time.sleep() calls.

I'll leave this assigned to me for a few more days, but it's 
unlikely I'll find time to "do something" about it.

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