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https://issues.apache.org/jira/browse/CASSANDRA-1954?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12996734#comment-12996734
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Stu Hood commented on CASSANDRA-1954:
-------------------------------------
I like this.
Nitpick: rather than nesting most of the body of {{maybeSwitchMemtable}} inside
{{if (oldMemtable.markPendingFlush())}}, you could negate and return early.
> Double-check or replace RRW memtable lock
> -----------------------------------------
>
> Key: CASSANDRA-1954
> URL: https://issues.apache.org/jira/browse/CASSANDRA-1954
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Stu Hood
> Priority: Minor
> Attachments:
> 0001-Double-check-in-maybeSwitchMemtable-to-minimize-writeL.txt,
> 0001-Remove-flusherLock-readLock.patch, 1954-v2.txt
>
>
> {quote}...when a Memtable reaches its threshold, up to (all) N write threads
> will often notice, and race to acquire the writeLock in order to freeze the
> memtable. This means that we do way more writeLock acquisitions than we need
> to...{quote}
> See CASSANDRA-1930 for backstory, but adding double checking inside a read
> lock before trying to re-entrantly acquire the writelock would eliminate most
> of these excess writelock acquisitions.
> Alternatively, we should explore removing locking from these structures
> entirely, and replacing the writeLock acquisition with a per-memtable counter
> of active threads.
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