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https://issues.apache.org/jira/browse/CASSANDRA-19986?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stefan Miklosovic updated CASSANDRA-19986:
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Description:
Currently prepared statements size are computed twice which is duplicate effort:
-
[https://github.com/apache/cassandra/blob/cassandra-4.0/src/java/org/apache/cassandra/cql3/QueryProcessor.java#L672]
-
[https://github.com/apache/cassandra/blob/cassandra-4.0/src/java/org/apache/cassandra/cql3/QueryProcessor.java#L802]
But we also get the side effect of that 'slow' computation locking the
underlying ConcurrentHashMap. We've had nodes becoming unresponsively slow for
hours with hundreds of threads in jstack all queued up behind
{{computeIfAbsent}} operations on cache insertion/eviction collisions.
Computing size only once and pulling that value instead of recomputing it on
cache insertion was the solution
was:
Currently prepared statements size are computed twice which is duplicate effort:
-
https://github.com/apache/cassandra/blob/cassandra-4.0/src/java/org/apache/cassandra/cql3/QueryProcessor.java#L672
-
https://github.com/apache/cassandra/blob/cassandra-4.0/src/java/org/apache/cassandra/cql3/QueryProcessor.java#L802
But we also get the side effect of that 'slow' computation locking the
underlying ConcurrentHashMap. We've had nodes becoming unresponsively slow for
hours with hundreds of threads in jstack all queued up behind
{{computeIbAbsent}} operations on cache insertion/eviction collisions.
Computing size only once and pulling that value instead of recomputing it on
cache insertion was the solution
> Prepared statements cache computation improvements
> --------------------------------------------------
>
> Key: CASSANDRA-19986
> URL: https://issues.apache.org/jira/browse/CASSANDRA-19986
> Project: Cassandra
> Issue Type: Improvement
> Components: Legacy/CQL
> Reporter: Berenguer Blasi
> Assignee: Berenguer Blasi
> Priority: Normal
> Fix For: 4.0.x, 4.1.x, 5.0.x, 5.1
>
>
> Currently prepared statements size are computed twice which is duplicate
> effort:
> -
> [https://github.com/apache/cassandra/blob/cassandra-4.0/src/java/org/apache/cassandra/cql3/QueryProcessor.java#L672]
> -
> [https://github.com/apache/cassandra/blob/cassandra-4.0/src/java/org/apache/cassandra/cql3/QueryProcessor.java#L802]
> But we also get the side effect of that 'slow' computation locking the
> underlying ConcurrentHashMap. We've had nodes becoming unresponsively slow
> for hours with hundreds of threads in jstack all queued up behind
> {{computeIfAbsent}} operations on cache insertion/eviction collisions.
> Computing size only once and pulling that value instead of recomputing it on
> cache insertion was the solution
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