[jboss-jira] [JBoss JIRA] (JGRP-1414) Synchronizing on 'members' MessageDispatcher.cast() is a contention point

[Bela Ban (JIRA)]

     [ https://issues.jboss.org/browse/JGRP-1414?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Bela Ban updated JGRP-1414:
---------------------------

       Fix Version/s: 3.1
    Git Pull Request: https://github.com/belaban/JGroups/pull/23  (was: https://github.com/belaban/JGroups/pull/23)

    
> Synchronizing on 'members' MessageDispatcher.cast() is a contention point
> -------------------------------------------------------------------------
>
>                 Key: JGRP-1414
>                 URL: https://issues.jboss.org/browse/JGRP-1414
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 3.0.2
>            Reporter: Manik Surtani
>            Assignee: Manik Surtani
>              Labels: concurrency, performance
>             Fix For: 3.0.3, 3.1
>
>         Attachments: TreeSet.png
>
>
> MessageDispatcher.cast() synchronizes on {{members}} and copies it to a local collection if {{null}} is passed in as your destination list.  This is a contention point if you have many concurrent threads attempting to cast() to the entire cluster, as they start queueing up at this point.
> Guarding {{members}} with a ReadWriteLock is probably a better approach, allowing {{members}} to be read safely and concurrently.
> However, since {{members}} is protected, I am not sure of the implications around this.  But then again, there is no guarantee that subclasses/extensions synchronize on {{members}} anyway.

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