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From "Alex Rudyy (Jira)" <j...@apache.org>
Subject [jira] [Updated] (QPID-8436) [Broker-J] [7.0.x] Improve performance of dequeuing old queue entries on triggering ring policy
Date Fri, 03 Apr 2020 13:58:00 GMT

     [ https://issues.apache.org/jira/browse/QPID-8436?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Alex Rudyy updated QPID-8436:
    Status: Reviewable  (was: In Progress)

> [Broker-J] [7.0.x] Improve performance of dequeuing old queue entries on triggering ring
> -----------------------------------------------------------------------------------------------
>                 Key: QPID-8436
>                 URL: https://issues.apache.org/jira/browse/QPID-8436
>             Project: Qpid
>          Issue Type: Improvement
>          Components: Broker-J
>            Reporter: Alex Rudyy
>            Assignee: Alex Rudyy
>            Priority: Major
>             Fix For: qpid-java-broker-7.0.9
> The performance of dequeuing old queue entries with triggering ring policy is affected
by the following factors:
>  * the oldest entry is not deleted immediately. As result, the deletion of the same oldest
entry can be requested from multiple publishing IO threads
>  * only one publishing thread can acquire the message with {{QueueEntry#acquireOrSteal}},
whilst the rest of publishing IO threads would set a {{DelayedAcquisitionStateListener}}.
As result, thousands of {{DelayedAcquisitionStateListeners}} can be potentially set on the
same queue entry
> * Setting of {{DelayedAcquisitionStateListeners}} from concurrent IO threads can consume
host CPU up to 100% as there is a tight loop in {{StateChangeListenerEntry#add(StateChangeListenerEntry<T,E>)}}.
There is a risk of running into defect {{QPID-8393}} whilst setting a listener.
> * The old message is deleted in IO thread blocking the enqueing of new messages
>  It seems that high CPU consumption on setting of {{DelayedAcquisitionStateListeners}}
is the main contributor for the perfromance degradation on old entries dequeueing by ring
> The current approach for dequeuing of old queue entries from ring policy should be revisited.
We need a mechanism to avoid multiple dequeueing of the same queue entry from concurrent threads.
Only after introduction of such mechanism we can look into further performance optimisation
for deletion of persistent queue entries.
> AutoCommitTransaction is used to dequeue entries on message expiration or breaching ring
policy threshold. As result, the dequeueing operation for persistent queue entry blocks until
queue entry record is removed from the store and the underlying store transaction is synced
to disk. The sequential removal of multiple entries can results in unnecessary delays due
to syncing disk on every dequeue.
> The broker performance for the corner cases described above can be significantly improved
by using asynchronous transactions in dequeue operations.
> Asynchronous transaction does not wait for the store dequeue transaction to sync to disk.
As result, the performance of removal unneeded queue entries can increase.

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