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From "Brian Bouterse (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (QPID-6836) qpid.messaging hangs in child forked process
Date Wed, 11 Nov 2015 22:47:11 GMT

    [ https://issues.apache.org/jira/browse/QPID-6836?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15001275#comment-15001275
] 

Brian Bouterse commented on QPID-6836:
--------------------------------------

This ended up not being related to the root cause of the issue I saw. I don't believe qpid.messaging
has any fork safety problems currently.

> qpid.messaging hangs in child forked process
> --------------------------------------------
>
>                 Key: QPID-6836
>                 URL: https://issues.apache.org/jira/browse/QPID-6836
>             Project: Qpid
>          Issue Type: Bug
>          Components: Python Client
>    Affects Versions: 0.32
>            Reporter: Brian Bouterse
>
> A python process that uses qpid.messaging and then forks causes qpid.messaing use in
the child process to randomly hang. To reproduce:
> 1. in a python process instantiate a qpid.messaing client and call open()
> 2. Call os.fork()
> 3. Try to instantiate another qpid.messaging client and call open()
> 4. observe the child process is waiting on a file descriptor that is shared with the
parent which will never wake up.
> Here is a potential reproducer with actual python code (from kgiusti):
> {code:none}
> #!/usr/bin/env python
> #
> # Licensed to the Apache Software Foundation (ASF) under one
> # or more contributor license agreements.  See the NOTICE file
> # distributed with this work for additional information
> # regarding copyright ownership.  The ASF licenses this file
> # to you under the Apache License, Version 2.0 (the
> # "License"); you may not use this file except in compliance
> # with the License.  You may obtain a copy of the License at
> # 
> #   http://www.apache.org/licenses/LICENSE-2.0
> # 
> # Unless required by applicable law or agreed to in writing,
> # software distributed under the License is distributed on an
> # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
> # KIND, either express or implied.  See the License for the
> # specific language governing permissions and limitations
> # under the License.
> #
> import optparse, time
> from qpid.messaging import *
> from qpid.util import URL
> from qpid.log import enable, DEBUG, WARN
> import os
> import sys
> def nameval(st):
>   idx = st.find("=")
>   if idx >= 0:
>     name = st[0:idx]
>     value = st[idx+1:]
>   else:
>     name = st
>     value = None
>   return name, value
> parser = optparse.OptionParser(usage="usage: %prog [options] ADDRESS [ CONTENT ... ]",
>                                description="Send messages to the supplied address.")
> parser.add_option("-b", "--broker", default="localhost",
>                   help="connect to specified BROKER (default %default)")
> parser.add_option("-r", "--reconnect", action="store_true",
>                   help="enable auto reconnect")
> parser.add_option("-i", "--reconnect-interval", type="float", default=3,
>                   help="interval between reconnect attempts")
> parser.add_option("-l", "--reconnect-limit", type="int",
>                   help="maximum number of reconnect attempts")
> parser.add_option("-c", "--count", type="int", default=1,
>                   help="stop after count messages have been sent, zero disables (default
%default)")
> parser.add_option("-d", "--durable", action="store_true",
>                   help="make the message persistent")
> parser.add_option("-t", "--timeout", type="float", default=None,
>                   help="exit after the specified time")
> parser.add_option("-I", "--id", help="use the supplied id instead of generating one")
> parser.add_option("-S", "--subject", help="specify a subject")
> parser.add_option("-R", "--reply-to", help="specify reply-to address")
> parser.add_option("-P", "--property", dest="properties", action="append", default=[],
>                   metavar="NAME=VALUE", help="specify message property")
> parser.add_option("-M", "--map", dest="entries", action="append", default=[],
>                   metavar="KEY=VALUE",
>                   help="specify map entry for message body")
> parser.add_option("-v", dest="verbose", action="store_true",
>                   help="enable logging")
> opts, args = parser.parse_args()
> if opts.verbose:
>   enable("qpid", DEBUG)
> else:
>   enable("qpid", WARN)
> if opts.id is None:
>   spout_id = str(uuid4())
> else:
>   spout_id = opts.id
> if args:
>   addr = args.pop(0)
> else:
>   parser.error("address is required")
> content = None
> content_type = None
> if args:
>   text = " ".join(args)
> else:
>   text = None
> if opts.entries:
>   content = {}
>   if text:
>     content["text"] = text
>   for e in opts.entries:
>     name, val = nameval(e)
>     content[name] = val
> else:
>   content = text
>   # no entries were supplied, so assume text/plain for
>   # compatibility with java (and other) clients
>   content_type = "text/plain"
> import pdb
> conn = Connection(opts.broker,
>                   reconnect=opts.reconnect,
>                   reconnect_interval=opts.reconnect_interval,
>                   reconnect_limit=opts.reconnect_limit)
> conn.open()
> print("Conn open")
> pid = os.fork()
> if not pid:
>     #child
>     try:
>         #pdb.set_trace()
>         ssn = conn.session()
>         snd = ssn.sender(addr)
>         count = 0
>         start = time.time()
>         while (opts.count == 0 or count < opts.count) and \
>               (opts.timeout is None or time.time() - start < opts.timeout):
>             msg = Message(subject=opts.subject,
>                           reply_to=opts.reply_to,
>                           content=content)
>             if opts.durable:
>                 msg.durable = True
>             if content_type is not None:
>                 msg.content_type = content_type
>             msg.properties["spout-id"] = "%s:%s" % (spout_id, count)
>             for p in opts.properties:
>                 name, val = nameval(p)
>                 msg.properties[name] = val
>             snd.send(msg)
>             count += 1
>             print msg
>     except:
>         print("booboo")
>         os._exit(1)
>     print("buh-bye")
>     os._exit(0)
> else:
>     status = os.wait()[1]
>     #pdb.set_trace()
>     conn.close()
>     sys.exit(status)
> {code}



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