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Date: Tue, 2 Apr 2013 16:51:15 +0000 (UTC)
From: "Vijay (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
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Subject: [jira] [Updated] (CASSANDRA-4860) Estimated Row Cache Entry size
 incorrect (always 24?)
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     [ https://issues.apache.org/jira/browse/CASSANDRA-4860?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Vijay updated CASSANDRA-4860:
-----------------------------

    Attachment: 4860-perf-test.zip

Ryan, Micro benchmark shows v3 is better, is there any chance you are hitting the same key in the key cache often? The reason for asking is that you might have a smaller key cache since the calculation is more accurate. If yes then i would increase the keycache and try. 

To be clear the Meter.measure() is bug and cannot be used in production and can cause OOM.
                
> Estimated Row Cache Entry size incorrect (always 24?)
> -----------------------------------------------------
>
>                 Key: CASSANDRA-4860
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-4860
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>    Affects Versions: 1.1.0, 1.2.3, 2.0
>            Reporter: Chris Burroughs
>            Assignee: Vijay
>             Fix For: 1.2.0 beta 3
>
>         Attachments: 0001-4860-v2.patch, 0001-4860-v3.patch, 0001-CASSANDRA-4860-for-11.patch, 0001-CASSANDRA-4860.patch, 4860-perf-test.zip, trunk-4860-revert.patch
>
>
> After running for several hours the RowCacheSize was suspicious low (ie 70 something MB)  I used  CASSANDRA-4859 to measure the size and number of entries on a node:
> In [3]: 1560504./65021
> Out[3]: 24.0
> In [4]: 2149464./89561
> Out[4]: 24.0
> In [6]: 7216096./300785
> Out[6]: 23.990877204647838
> That's RowCacheSize/RowCacheNumEntires  .  Just to prove I don't have crazy small rows the mean size of the row *keys* in the saved cache is 67 and Compacted row mean size: 355.  No jamm errors in the log
> Config notes:
> row_cache_provider: ConcurrentLinkedHashCacheProvider
> row_cache_size_in_mb: 2048
> Version info:
>  * C*: 1.1.6
>  * centos 2.6.32-220.13.1.el6.x86_64
>  * java 6u31 Java HotSpot(TM) 64-Bit Server VM (build 20.6-b01, mixed mode)

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