[jira] Commented: (FELIX-1746) Reduce contention on ServiceRegistry.getServiceReferences(String, Filter)

["Karl Pauls (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FELIX-1746?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12765031#action_12765031 ] 

Karl Pauls commented on FELIX-1746:
-----------------------------------

I had a look at your patch and I think it is not unreasonable at all. However, I think I have a different solution that doesn't introduce new classes and has less potential to introduce semantic  changes we might not want. Could you please try the attached patch (FELIX-1746-alt.patch) and see whether that removes the contention equally well and let me know?

> Reduce contention on ServiceRegistry.getServiceReferences(String, Filter)
> -------------------------------------------------------------------------
>
>                 Key: FELIX-1746
>                 URL: https://issues.apache.org/jira/browse/FELIX-1746
>             Project: Felix
>          Issue Type: Improvement
>          Components: Framework
>    Affects Versions: felix-2.0.0
>            Reporter: Jed Wesley-Smith
>         Attachments: blocked-threads.gif.jpg, FELIX-1746-alt.patch, FELIX-1746.patch
>
>
> Performance testing has shown that there is significant contention on the ServiceRegistry object's monitor during startup. This is caused by Spring DM making lots of calls to the synchronized method ServiceRegistry.getServiceReferences(String, Filter). This method is synchronized in order to protect the m_serviceRegsMap HashMap, but the method does a lot more work than simply accessing the map.
> Propose changing the ServiceRegistry to use a thread-safe Map implementation that does not require external synchronization, in particular a CopyOnWriteMap. I will add a patch that includes a CopyOnWriteMap implementation.

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