New submission from Alex Roitman <rsh...@gmail.com>:
Importing the module with the following contents results in RuntimeError:
==================
import os
pid = os.fork()
if pid == 0:
print "In the child"
else:
print "In the parent"
print "Done\n"
==================
Running the same module as main works just fine, so it seems to be a purely
import issue.
I looked into the 2.6.6rc1 source. This is what I think happens in
Python/import.c file:
1. After the fork() call, _PyImport_ReInitLock() is run. It sets
import_lock_thread to -1 in the child, line 310.
2. In _PyImport_ReleaseLock() line 290 compares import_loc_thread to the
current thread id, and if they are not the same then -1 is returned, which
results in RuntimeError in PyImport_ImportModuleLevel (line 2186-2189)
So this is guaranteed to happen in the child, every time fork() is executed
inside the module being imported. If I change line 290 to be:
if (import_lock_thread != me && import_lock_thread != -1)
then import proceeds fine, although I'm not sure this is a proper solution.
This happens on Linux, Darwin, and Cygwin, with python 2.6.5 and higher. I'd be
happy to assist solving this, please let me know how I can help.
----------
components: Interpreter Core
messages: 113643
nosy: Alex.Roitman
priority: normal
severity: normal
status: open
title: imporing a module that executes fork() raises RuntimeError
type: behavior
versions: Python 2.6, Python 2.7
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Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue9573>
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