[jira] [Created] (QPID-6740) Message not delivered after "empty" exception

["Viktor Horvath (JIRA)" <ji...@apache.org>]

Viktor Horvath created QPID-6740:
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             Summary: Message not delivered after "empty" exception
                 Key: QPID-6740
                 URL: https://issues.apache.org/jira/browse/QPID-6740
             Project: Qpid
          Issue Type: Bug
          Components: C++ Broker, Python Client
    Affects Versions: 0.32
         Environment: CentOS 7.1
qpid (C++) 0.32, qpid-python 0.32
            Reporter: Viktor Horvath


If this is not a bug, the documentation might need an update, as I'm not aware of what I did wrong :-)

Here is a test case, you will need two ipython consoles.
{code:title=console 1}
from qpid.messaging import Connection

session = Connection.establish('amqp://127.0.0.1').session()
sender = session.sender(
    'mytestqueue; {create: always, node: {durable: True, type: queue}}')
cleaner = session.receiver('mytestqueue')
cleaner.fetch(timeout=0) # will raise a qpid.messaging.exceptions.Empty
{code}
(The receiver is named _cleaner_ because it is only supposed to "free" the queue from any old messages.)

{code:title=console 2}
from qpid.messaging import Connection

session = Connection.establish('amqp://127.0.0.1').session()
receiver = session.receiver('mytestqueue')
receiver.fetch()
{code}

Back to the first console:
{code:title=console 1}
sender.send({'msg': 'test'})
{code}

*This message does not arrive at the second console. The receiver.fetch() still blocks.*

I have the following observations about this situation:
# One workaround is to call cleaner.close(), the blocking receiver will immediately return the message.
# Another workaround is to specify a time-out in the receiver.fetch() call (test it with timeout=60). The message will be returned, though only at the end of the time-out!
# Sending a second message will result in immediate delivery of the first message.
# Once the situation is unblocked, you have to start anew in order to experience the blocking situation again. Don't forget to call session.acknowledge() before ending the console 2, or use a fresh queue.
# The problem only manifests itself when receiver.fetch() starts before the message is sent.



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