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From "graham sanderson (JIRA)" <j...@apache.org>
Subject [jira] [Comment Edited] (CASSANDRA-6944) liveRatio jumps to max when Memtable is empty
Date Wed, 06 Aug 2014 07:49:12 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14087384#comment-14087384
] 

graham sanderson edited comment on CASSANDRA-6944 at 8/6/14 7:48 AM:
---------------------------------------------------------------------

Note I haven't looked closely but presumably empty memtables happen as a result of the active
memtable changing while MeteringRunnable is waiting, and in this case we may not actually
want to update the liveRatio, so this warning actually does indicate a problem (in the code)


was (Author: graham sanderson):
Note I haven't looked closely but presumably empty memtables happen as a result of the active
memtable changing while MeteringRunnable is waiting

> liveRatio jumps to max when Memtable is empty
> ---------------------------------------------
>
>                 Key: CASSANDRA-6944
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6944
>             Project: Cassandra
>          Issue Type: Bug
>          Components: Core
>         Environment: SUSE Linux Enterprise 11 (64-bit)
>            Reporter: Erik Hansen
>            Assignee: Aleksey Yeschenko
>            Priority: Minor
>              Labels: memtables
>
> liveRatio calculation on an empty memtable results in a value of Infinity since memtable.currentSize=0.
 Infinity then gets capped at the liveRatio max of 64.
> {noformat}
> WARN [MemoryMeter:1] 2014-03-19 09:26:59,483 Memtable.java (line 441) setting live ratio
to maximum of 64.0 instead of Infinity
> INFO [MemoryMeter:1] 2014-03-19 09:26:59,485 Memtable.java (line 452) CFS(Keyspace='system',
ColumnFamily='compactions_in_progress') liveRatio is 64.0 (just-counted was 64.0).  calculation
took 7ms for 0 cells
> {noformat}
> Jumping liveRatio to the max value based on an empty Memtable leads to more frequent
flushing than may be necessary.
> CASSANDRA-4243 previously addressed this issue, but was resolved as fixed by CASSANDRA-3741.
 It does not appear this issue has been fixed as of 2.0.5



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