[New-bugs-announce] [issue18277] Queue is empty right after put from the same process/thread

[shwouchk]

New submission from shwouchk:

Consider this:

$ python
Python 2.7.4 (default, Apr 19 2013, 18:28:01) 
[GCC 4.7.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import multiprocessing as mp
>>> q = mp.Queue()
>>> while True:
       q.put(1)
       q.get_nowait()

Traceback (most recent call last):
  File "<stdin>", line 3, in <module>
  File "/usr/lib/python2.7/multiprocessing/queues.py", line 152, in get_nowait
    return self.get(False)
  File "/usr/lib/python2.7/multiprocessing/queues.py", line 134, in get
    raise Empty
Queue.Empty

I believe that similar behavior could be seen in cPython 2.7.3 with the Queue.Queue implementation, but I can't reproduce it now and don't have the old version to test. And it is irrelevant anyway since it work "correctly" now.

I think this behavior is counter intuitive and hampers the development of code that performs stuff with queues in a generic way and works in both single and multi-process environments.

----------
components: IO, Interpreter Core
messages: 191566
nosy: shwouchk
priority: normal
severity: normal
status: open
title: Queue is empty right after put from the same process/thread
type: behavior
versions: Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue18277>
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