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https://issues.apache.org/jira/browse/CASSANDRA-7359?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14020115#comment-14020115
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Aleksey Yeschenko commented on CASSANDRA-7359:
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I don't mind replacing Object-s with Lock-s. I am against complicating the code
for an unproven reason, though.
Would simply replacing the Object[] array with Guava's Striped make you happy?
(like we have at
https://github.com/iamaleksey/cassandra/blob/trunk/src/java/org/apache/cassandra/db/Keyspace.java#L66)
?
Nothing wrong with Benedict's patch (most likely), other than we are both
pretty sure we don't need it.
> Optimize locking in PaxosState
> ------------------------------
>
> Key: CASSANDRA-7359
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7359
> Project: Cassandra
> Issue Type: Improvement
> Reporter: sankalp kohli
> Assignee: Benedict
> Priority: Minor
> Attachments: 7359.txt
>
>
> In PaxosState, we want to lock on same rows and have created 1024 size array
> with java Objects in them to be used for locking.
> We should replace these Objects with some Lock so that we can know whether
> there is contention trying to acquire a lock for different rows.
> We can achieve that by also storing the hash of the row which acquired the
> lock. This will tell us if this needs to be improved.
> Here is an improvement which I was thinking about.
> Say two rows A and B map to the same 1024 bucket which we have. A get the
> lock and B has to wait. Here B can check if his hash is different and create
> a new object and chain it to the other one.
> This looks close to a hashMap with chaining for same key.
> The hard part will be removing the entries no longer being used.
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