[jira] [Created] (CASSANDRA-5939) Cache Providers calculate very different row sizes

["Chris Burroughs (JIRA)" <ji...@apache.org>]

Chris Burroughs created CASSANDRA-5939:
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             Summary: 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


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

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