[jira] [Commented] (CASSANDRA-6944) liveRatio jumps to max when Memtable is empty

["graham sanderson (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/CASSANDRA-6944?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14087329#comment-14087329 ] 

graham sanderson commented on CASSANDRA-6944:
---------------------------------------------

We just upgraded to 2.0.9 (from 2.0.5)

Lots more {{Memtable.java (line 470) setting live ratio to maximum of 64.0 instead of Infinity}}

Note quite sure when this is ever a useful warning? ... when you say:

{quote}
I say it's not a problem after CASSANDRA-6945
...
So as soon as some data starts flowing into the memtable, the ratio will be recalculated. 64 will never stuck for long.
{quote}

I'm not sure if you are implying that empty memtables should be rare, or what... but there are now LOTS of warnings, which is either bad or not.


> 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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