cassandra-commits mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From "Chris Burroughs (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-5939) Cache Providers calculate very different row sizes
Date Fri, 30 Aug 2013 13:17:57 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-5939?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13754676#comment-13754676
] 

Chris Burroughs commented on CASSANDRA-5939:
--------------------------------------------

Enable ROWS_ONLY caching on Standard1 from, wrote data, restarted and read data until row
cache was full.  Used 1024 MB ConcurrentLinkedHashCacheProvider.

 * entries: 12,386
 * RowCacheSize: 1,073,680,880

Stop reading, run gc through jconsole.  RowCacheSize remains 1,073,680,880 but total heap
used is 108,779,240.  From a heap dump yourkit estimated the retained size of the ConcurrentLinkedHashCache
at 37,481,616, but I'm not sure how relevant that calculation is.  I'm not sure what the correct
value, is but the estimated row cache size can't possible be correct since it is far larger
than total used heap.
                
> Cache Providers calculate very different row sizes
> --------------------------------------------------
>
>                 Key: CASSANDRA-5939
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-5939
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: 1.2.8
>            Reporter: Chris Burroughs
>            Assignee: Vijay
>
> Took the same production node and bounced it 4 times comparing version and cache provider.
 ConcurrentLinkedHashCacheProvider and SerializingCacheProvider produce very different results
resulting in an order of magnitude difference in rows cached.  In all cases the row cache
size was 2048 MB.  Hit rate is provided for color, but entries & size are the important
part.
> 1.2.8 ConcurrentLinkedHashCacheProvider:
>  * entries: 23,217
>  * hit rate: 43%
>  * size: 2,147,398,344
> 1.2.8 about 20 minutes of SerializingCacheProvider:
>  * entries: 221,709
>  * hit rate: 68%
>  * size: 18,417254
> 1.2.5 ConcurrentLinkedHashCacheProvider:
>  * entries: 25,967
>  * hit rate: ~ 50%
>  * size:  2,147,421,704
> 1.2.5 about 20 minutes of SerializingCacheProvider:
>  * entries: 228,457
>  * hit rate: ~ 70%
>  * size: 19,070,315
> A related(?) problem is that the ConcurrentLinkedHashCacheProvider sizes seem to be highly
variable.  Digging up the values for 5 different nodes in the cluster using ConcurrentLinkedHashCacheProvider
shows a wide variance in number of entries:
>  * 12k
>  * 444k
>  * 10k
>  * 25k
>  * 25k

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira

Mime
View raw message