[issue4660] multiprocessing.JoinableQueue task_done() issue

[Brian]

Brian <br...@merrells.org> added the comment:

Hey Jesse,
It was good meeting you at Pycon.  I don't have anything handy at the moment
although, if memory serves, the most trivial of example seemed to illustrate
the problem.  Basically any situation where a joinable queue would keep
bumping up against being empty (ie retiring items faster than they are being
fed), and does enough work between get() and task_done() to be preempted
would eventually break.  FWIW I was running on a Windows box.

I am afraid I am away from my computer until late tonight but I can try to
cook something up then (I presume you are sprinting today?).  Also I think
the issue becomes clear when you think about what happens if
joinablequeue.task_done() gets preempted between its few lines.

-brian

On Mon, Mar 30, 2009 at 2:55 PM, Jesse Noller <rep...@bugs.python.org>wrote:

>
> Jesse Noller <jnol...@gmail.com> added the comment:
>
> Hi Brian - do you have a chunk of code that exacerbates this? I'm having
> problems reproducing this, and need a test so I can prove out the fix.
>
> ----------
>
> _______________________________________
> Python tracker <rep...@bugs.python.org>
> <http://bugs.python.org/issue4660>
> _______________________________________
>

----------
Added file: http://bugs.python.org/file13485/unnamed

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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue4660>
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Hey Jesse,<div><br></div><div>It was good meeting you at Pycon.  I don&#39;t 
have anything handy at the moment although, if memory serves, the most trivial 
of example seemed to illustrate the problem.  Basically any situation where a 
joinable queue would keep bumping up against being empty (ie retiring items 
faster than they are being fed), and does enough work between get() and 
task_done() to be preempted would eventually break.  FWIW I was running on a 
Windows box.</div>

<div><br></div><div>I am afraid I am away from my computer until late tonight 
but I can try to cook something up then (I presume you are sprinting today?). 
 Also I think the issue becomes clear when you think about what happens if 
joinablequeue.task_done() gets preempted between its few lines.</div>

<div><br></div><div>-brian</div><div><br></div><div><div class="gmail_quote">On 
Mon, Mar 30, 2009 at 2:55 PM, Jesse Noller <span dir="ltr">&lt;<a 
href="mailto:rep...@bugs.python.org";>rep...@bugs.python.org</a>&gt;</span> 
wrote:<br>

<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc 
solid;padding-left:1ex;"><br>
Jesse Noller &lt;<a href="mailto:jnol...@gmail.com";>jnol...@gmail.com</a>&gt; 
added the comment:<br>
<br>
Hi Brian - do you have a chunk of code that exacerbates this? I&#39;m having<br>
problems reproducing this, and need a test so I can prove out the fix.<br>
<br>
----------<br>
<div><div></div><div class="h5"><br>
_______________________________________<br>
Python tracker &lt;<a 
href="mailto:rep...@bugs.python.org";>rep...@bugs.python.org</a>&gt;<br>
&lt;<a href="http://bugs.python.org/issue4660"; 
target="_blank">http://bugs.python.org/issue4660</a>&gt;<br>
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</div></div></blockquote></div><br></div>

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