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From "Sylvain Lebresne (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, 31 Oct 2011 15:21:32 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13140221#comment-13140221
] 

Sylvain Lebresne commented on CASSANDRA-3427:
---------------------------------------------

Quite honestly, the best workaround is likely to apply the attached patch on top of 1.0.1
(you can wait for someone to review to get a bit more confidence).

Because yes, a bigger chunk_length would diminish the problem, but if you do enough range_queries
you would likely still OOM and there is point after which a chunk_length too big is just counter-productive.

                
> 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: 1.0.1
>            Reporter: Sylvain Lebresne
>            Assignee: Sylvain Lebresne
>              Labels: compression
>             Fix For: 1.0.2
>
>         Attachments: 3427.patch
>
>
> 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.

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