Notification - when no listenere without pool exist the notification queue is not consumed

[Harald Jensås]

The oslo messaging documentation[1] how pools can be used with notifications to make multiple subgroups of listeners recive copies of the notification.

When all listeners use a pool, there are no listeners consuming the notification queue that notifiers publish messages too. This queue will continue to grow, as can bee seen below queue listing:

rabbitmqctl list_queues name messages consumers auto_delete

Listing queues ...
pool-listener 0 1 false
test-topic.info 293 0 false

The atteched file contains a small reproducer.
 notfier.py - Sends notifications
 listener.py - A notification listener that does not use a pool
 pool-listener.py - A notification listener using a pool

When running notfier.py and pool-listener.py only the test-topic.info queue have no consumers and continues to grow.

Some mechanism should clear the messages of the test-topic.info queue when all listeners are using one of more pools.

[1] https://github.com/openstack/oslo.messaging/blob/master/oslo_messaging/notify/listener.py#L27-L33

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/642442

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/642442
Committed: https://git.openstack.org/cgit/openstack/oslo.messaging/commit/?id=855a85fa2daca96ab7d13d5db7684f241a7c18b3
Submitter: Zuul
Branch: master

commit 855a85fa2daca96ab7d13d5db7684f241a7c18b3
Author: Kenneth Giusti <email address hidden>
Date: Mon Mar 11 09:31:38 2019 -0400

    Clarify the documentation for pooled Notification Listeners

    Change-Id: I184b045edaa8e61f075df576992426e94bf7386a
    Closes-Bug: #1814544

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/oslo.messaging 9.6.0 release.