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From "T Jake Luciani (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-4860) Estimated Row Cache Entry size incorrect (always 24?)
Date Tue, 07 May 2013 21:43:17 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-4860?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13651344#comment-13651344
] 

T Jake Luciani commented on CASSANDRA-4860:
-------------------------------------------

I think the issue is the RowIndexEntry size. If you look at IndexInfo.memorySize() those bytebuffers
would have the wrong capacity since we mmap them...

{code}
        public long memorySize()
        {
            long fields = ObjectSizes.getSize(firstName) + ObjectSizes.getSize(lastName) +
8 + 8; 
            return ObjectSizes.getFieldSize(fields);
        }
{code}

                
> 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, 4860-tests.patch, 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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