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From "Brandon Williams (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-7974) Enable tooling to detect hot partitions
Date Fri, 19 Sep 2014 22:33:34 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-7974?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14141453#comment-14141453
] 

Brandon Williams commented on CASSANDRA-7974:
---------------------------------------------

Looks like StreamSummary isn't threadsafe, synchronizing the addSample method fixes it.  I'm
sure it costs some performance, but maybe that's acceptable when the user has control over
the window and just wants to know what's going on.

> Enable tooling to detect hot partitions
> ---------------------------------------
>
>                 Key: CASSANDRA-7974
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-7974
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Brandon Williams
>            Assignee: Brandon Williams
>         Attachments: 7974.txt
>
>
> Sometimes you know you have a hot partition by the load on a replica set, but have no
way of determining which partition it is.  Tracing is inadequate for this without a lot of
post-tracing analysis that might not yield results.  Since we already include stream-lib for
HLL in compaction metadata, it shouldn't be too hard to wire up topK for X seconds via jmx/nodetool
and then return the top partitions hit.



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