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From "Jonathan Ellis (Commented) (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-3427) CompressionMetadata is not shared across threads, we create a new one for each read
Date Mon, 14 Nov 2011 14:30:51 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13149650#comment-13149650
] 

Jonathan Ellis commented on CASSANDRA-3427:
-------------------------------------------

I can get you a place to upload the heap dump from an OOM too.  (8GB would be best, since
heap analysis requires ram proportional to the heap size.)

To rule out the obvious, have you tried running 1.0.x w/o compression?
                
> CompressionMetadata is not shared across threads, we create a new one for each read
> -----------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-3427
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3427
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.0.0
>            Reporter: Sylvain Lebresne
>            Assignee: Sylvain Lebresne
>              Labels: compression
>             Fix For: 1.0.2
>
>         Attachments: 0001-debugging.patch, 3427.patch, 3427_v2.patch, CASSANDRA-3427.patch,
jmx_jvm_memory-month.png, jmx_jvm_memory-week.png
>
>
> The CompressionMetada holds the compressed block offsets in memory. Without being absolutely
huge, this is still of non-negligible size as soon as you have a bit of data in the DB. Reallocating
this for each read is a very bad idea.
> Note that this only affect range queries, since "normal" queries uses CompressedSegmentedFile
that does reuse a unique CompressionMetadata instance.
> ( Background: http://thread.gmane.org/gmane.comp.db.cassandra.user/21362 )

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