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From "Mck SembWever (Issue Comment Edited) (JIRA)" <j...@apache.org>
Subject [jira] [Issue Comment Edited] (CASSANDRA-3427) CompressionMetadata is not shared across threads, we create a new one for each read
Date Mon, 14 Nov 2011 18:34:51 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-3427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13149796#comment-13149796
] 

Mck SembWever edited comment on CASSANDRA-3427 at 11/14/11 6:33 PM:
--------------------------------------------------------------------

version: 1.0.2 snapshot (pretty close to release date) + CASSANDRA-3197.
w/o compression: that would require a full compact/scrub. that takes close to 24hrs :-(
patch: i attach that and hopefully have output soon. a heap dump can be done at the same time...
                
      was (Author: michaelsembwever):
    version: 1.0.2 snapshot (pretty close to release date).
w/o compression: that would require a full compact/scrub. that takes close to 24hrs :-(
patch: i attach that and hopefully have output soon. a heap dump can be done at the same time...
                  
> 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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