On 2012-11-13 12:19, Jean-Michel Pichavant wrote:
Fellows,
I'm having problems understanding an issue with passing function as parameters.
I'm sending some functions to the multiprocessing module (python 2.5 with the
proper backport).
I'm iterating on a list of functions, however it seems that only the last
function implementation is used for
all the subprocesses.
Here's a code that triggers the issue:
import multiprocessing
def f1():
print 'I am f1'
def f2(foo):
print 'I am f2 %s' % foo
workers = [
(f1,tuple()),
(f2,(5,)),
]
procs=[]
for func, parameters in workers:
# here it should be decorated, but for this example to be kept simple, the
function is only wrapped, doing nothing special
def subproc(*args, **kwargs):
return func(*args, **kwargs)
procs.append(multiprocessing.Process(target=subproc, args=parameters))
for proc in procs:
proc.start()
for proc in procs:
proc.join()
Here's the result:
run test.py
Process Process-1:
Traceback (most recent call last):
File
"/usr/lib/python2.5/site-packages/multiprocessing-2.6.2.1-py2.5-linux-i686.egg/multiprocessing/process.py",
line 237, in _bootstrap
self.run()
File
"/usr/lib/python2.5/site-packages/multiprocessing-2.6.2.1-py2.5-linux-i686.egg/multiprocessing/process.py",
line 93, in run
self._target(*self._args, **self._kwargs)
File "test.py", line 17, in subproc
return func(*args, **kwargs)
TypeError: f2() takes exactly 1 argument (0 given)
I am f2 5
It looks like the first subprocess is called with f2 instead of f1.
I believe the problem is that 'subproc' calls 'func', which is rebound
on the each iteration.
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