[jira] [Created] (CASSANDRA-6574) key cache shrinks on restart

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

Chris Burroughs created CASSANDRA-6574:
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             Summary: key cache shrinks on restart
                 Key: CASSANDRA-6574
                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6574
             Project: Cassandra
          Issue Type: Bug
          Components: Core
         Environment: 1.2.12 + patches
            Reporter: Chris Burroughs


During a rolling restart the key number of entries the number of entries in the key cache is shrinking.  That is far fewer entries are loaded than are saved.  This has obvious bad consequences for post restart performance.

{noformat}
key_cache_size_in_mb: 48
key_cache_save_period: 900

# Number of keys from the key cache to save
# Disabled by default, meaning all keys are going to be saved
# key_cache_keys_to_save: 100

row_cache_size_in_mb: 256
row_cache_save_period: 300

row_cache_keys_to_save: 50000
row_cache_provider: SerializingCacheProvider
saved_caches_directory: /home/cassandra/shared/saved_caches
{noformat}

Same log lines:
{noformat}
 INFO [CompactionExecutor:24543] 2014-01-11 11:35:47,783 AutoSavingCache.java (line 289) Saved KeyCache (398028 items) in 1252 ms

*** RESTART ***

 INFO [main] 2014-01-11 11:44:59,608 AutoSavingCache.java (line 140) reading saved cache /home/cassandra/shared/saved_caches/ks-cf1-KeyCache-b.db
 INFO [main] 2014-01-11 11:45:00,509 AutoSavingCache.java (line 140) reading saved cache /home/cassandra/shared/saved_caches/ks-cf2-RowCache-b.db
 INFO [main] 2014-01-11 12:02:48,675 ColumnFamilyStore.java (line 452) completed loading (1068166 ms; 50000 keys) row cache for ks.cf2

 INFO [main] 2014-01-11 12:02:48,769 CassandraDaemon.java (line 291) completed pre-loading (67760 keys) key cache.
 INFO [main] 2014-01-11 12:02:48,769 CassandraDaemon.java (line 294) completed pre-loading (50000 keys) row cache.

 INFO [CompactionExecutor:1] 2014-01-11 12:02:49,133 AutoSavingCache.java (line 289) Saved RowCache (50000 items) in 266 ms
 INFO [CompactionExecutor:2] 2014-01-11 12:02:49,575 AutoSavingCache.java (line 289) Saved KeyCache (67760 items) in 707 ms
{noformat}



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