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Posted to commits@cassandra.apache.org by "Héctor Izquierdo (JIRA)" <ji...@apache.org> on 2011/07/09 15:27:16 UTC

[jira] [Created] (CASSANDRA-2875) Increase index_interval and reopen sstables on low heap situations

Increase index_interval and reopen sstables on low heap situations
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                 Key: CASSANDRA-2875
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2875
             Project: Cassandra
          Issue Type: Improvement
          Components: Core
    Affects Versions: 0.8.1
            Reporter: Héctor Izquierdo


One of the reasons that can cause an OOM is key indexes. Of course you can tune it, but that's after your node has crashed. Events like repair can cause a much bigger memory pressure than expected on normal operation. As part of the measures taken when heap is almost full it would be good if key indexes could be shrank. I don't know how indexes are stored in memory but I guess it would be possible to remove entries without rereading all sstables.

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[jira] [Resolved] (CASSANDRA-2875) Increase index_interval and reopen sstables on low heap situations

Posted by "Jonathan Ellis (JIRA)" <ji...@apache.org>.
     [ https://issues.apache.org/jira/browse/CASSANDRA-2875?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Jonathan Ellis resolved CASSANDRA-2875.
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    Resolution: Won't Fix

Sorry, it's too hard to tell when "low heap" is a transitory condition vs when the JVM is really in trouble.  We do our best by cutting row cache and flushing memtables (both relatively low-impact) but reopening sstables would cause more damage than good in a lot of situations.

> Increase index_interval and reopen sstables on low heap situations
> ------------------------------------------------------------------
>
>                 Key: CASSANDRA-2875
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-2875
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Core
>    Affects Versions: 0.8.1
>            Reporter: Héctor Izquierdo
>
> One of the reasons that can cause an OOM is key indexes. Of course you can tune it, but that's after your node has crashed. Events like repair can cause a much bigger memory pressure than expected on normal operation. As part of the measures taken when heap is almost full it would be good if key indexes could be shrank. I don't know how indexes are stored in memory but I guess it would be possible to remove entries without rereading all sstables.

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