[New-bugs-announce] [issue10527] multiprocessing.Pipe problem: "handle out of range in select()"

Gergely Kálmán report at bugs.python.org
Thu Nov 25 12:15:13 CET 2010

New submission from Gergely Kálmán <kalman.gergely at duodecad.hu>:


I have a code that uses multiprocessing.Pipe to communicate with subprocesses. Spawning 500 subprocesses this way works like a charm, but when spawning about 600 of them the pipe ends raise the exception: "handle out of range in select()". I realized that this is because of the FD_SETSIZE limit. To address the situation I quickly hacked together a patch that uses poll() instead of select(), which solves the problem for me. I don't know the reason why select() was chosen for this task (maybe because of windows) but wouldn't it be better to use polling where possible?

I've attached the tester. Beware, running it may use up all memory in your system, so be careful!

Gergely Kalman

components: Library (Lib)
files: tester.py
messages: 122349
nosy: synapse
priority: normal
severity: normal
status: open
title: multiprocessing.Pipe problem: "handle out of range in select()"
type: feature request
versions: Python 3.2
Added file: http://bugs.python.org/file19813/tester.py

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