[New-bugs-announce] [issue15440] multiprocess fails to re-raise exception which has mandatory arguments

[Bala FA]

New submission from Bala FA <barumuga at redhat.com>:

I use multiprocess in one of my project.  When an exception which
requires mandatory argument is raised by a server process, is not
re-raised properly to client process.  I get an error something like
below

Traceback (most recent call last):
  File "prod.py", line 69, in <module>
    main()
  File "prod.py", line 61, in main
    print myobj.fun3()
  File "<string>", line 2, in fun3
  File "/usr/lib64/python2.7/multiprocessing/managers.py", line 759,
in _callmethod
    kind, result = conn.recv()
TypeError: ('__init__() takes exactly 2 arguments (1 given)', <class
'__main__.MyException2'>, ())

However, if an exception which has optional argument is raised by
server process, is re-raised properly to client process.

Below is a reproducer.

#!/usr/bin/python

import sys
import os
import time
import subprocess
from multiprocessing.managers import BaseManager

class MyManager(BaseManager):
    pass

class MyException1(Exception):
    def __init__(self, msg=''):
        self.msg = msg

    def __str__(self):
        return self.msg

class MyException2(Exception):
    def __init__(self, msg):
        self.msg = msg

    def __str__(self):
        return self.msg

class MyClass(object):
    def fun1(self):
        return 'this is fun1'

    def fun2(self):
        raise MyException1('fun2 raised')

    def fun3(self):
        raise MyException2('fun3 raised')

def runManager():
    manager = MyManager(address=('', 50000), authkey='abc')
    manager.register('instance', callable=MyClass)
    server = manager.get_server()
    print "manager is running"
    server.serve_forever()

def startManager():
    p = subprocess.Popen(['python', __file__, 'manager'])
    time.sleep(1)
    return p

def main():
    p = startManager()
    manager = MyManager(address=('', 50000), authkey='abc')
    manager.register('instance')
    print "connecting to manager"
    manager.connect()
    myobj = manager.instance()
    print myobj.fun1()
    try:
        print myobj.fun2()
    except MyException1, e:
        print e
    try:
        print myobj.fun3()
    except MyException2, e:
        print e
    finally:
        p.kill()

if __name__ == '__main__':
    if len(sys.argv) == 1:
        main()
    else:
        runManager()

I use python 2.7.3 on fedora 17 on x86_64 (rpm version is
python-2.7.3-6.fc17.x86_64)

----------
components: Interpreter Core
messages: 166299
nosy: Bala.FA
priority: normal
severity: normal
status: open
title: multiprocess fails to re-raise exception which has mandatory arguments
type: crash
versions: Python 2.7

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue15440>
_______________________________________