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https://issues.apache.org/jira/browse/QPID-6740?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14791695#comment-14791695
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Pavel Moravec commented on QPID-6740:
-------------------------------------
Interesting use case.. Per my testing on upstream qpid (and 0.30 python-client
while the issue sounds to be on broker side, imho), I have reproducer for the
same using single python script:
{code}
from qpid.messaging import Connection
import threading
class ReceiverThread(threading.Thread):
def __init__(self,receiver):
super(ReceiverThread, self).__init__()
self.receiver=receiver
def run(self):
print receiver.fetch()
session1 = Connection.establish('amqp://127.0.0.1').session()
sender = session1.sender(
'mytestqueue; {create: always, node: {type: queue}}')
cleaner = session1.receiver('mytestqueue')
try:
print cleaner.fetch(timeout=0) # will raise a
qpid.messaging.exceptions.Empty
except Exception,e:
print e
session2 = Connection.establish('amqp://127.0.0.1').session()
receiver = session2.receiver('mytestqueue')
thread1 = ReceiverThread(receiver)
thread1.start()
sender.send({'msg': 'test'})
thread1.join()
{code}
In either case (using original reproducer or mine), broker does not send the
message anywhere. See e.g. "qpid-stat -q mytestqueue" and zero acquired
messages.
> [C++ broker, Python client] 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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