[jira] [Resolved] (GEODE-7245) Remove most uses of latestViewReadLock in GMSMembershipManager

["Kamilla Aslami (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/GEODE-7245?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Kamilla Aslami resolved GEODE-7245.
-----------------------------------
    Fix Version/s: 1.15.0
       Resolution: Fixed

> Remove most uses of latestViewReadLock in GMSMembershipManager
> --------------------------------------------------------------
>
>                 Key: GEODE-7245
>                 URL: https://issues.apache.org/jira/browse/GEODE-7245
>             Project: Geode
>          Issue Type: Improvement
>          Components: membership
>            Reporter: Bruce J Schuchardt
>            Assignee: Kamilla Aslami
>            Priority: Major
>              Labels: pull-request-available
>             Fix For: 1.15.0
>
>
> Changes for GEODE-7196 made the latestView immutable so there is no reason, in most cases, to use the latestViewReadlock when accessing the view. A simple volatile read of the field & storing the value in a method variable can replace most uses of the latestViewReadLock, especially those uses that are in the path of sending or receiving messages.
> Performance could be measured with our benchmarks to see if this change helps.
>  
> latestViewReadLock is currently used in getCoordinator(), memberExists(), getMembersNotShuttingDown(), getAllMembers(), isShunnedOrNew(), isSurpriseMember(), doWithViewLocked().
> doWithViewLocked() is used to add membership listeners, and we don't want the view to change until this operation completes. Therefore, we should keep the lock in this method.
> getCoordinator(), memberExists(), getMembersNotShuttingDown(), getAllMembers() use latestViewReadLock to access latestView. In these methods we can replace the lock with a volatile read of the latestView and storing the value in a method variable.
> isShunnedOrNew() accesses latestView, and 2 ConcurrentHashMaps - shunnedMembers and surpriseMembers. Since the hashmaps are concurrent and latestView is unmodifiable, a volatile read could replace the lock. Same for isSurpriseMember(), which uses surpriseMembers hashmap.



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