[
https://issues.apache.org/jira/browse/CASSANDRA-4065?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13233503#comment-13233503
]
Jonathan Ellis commented on CASSANDRA-4065:
-------------------------------------------
bq. meter runs never decrease liveRatio in Memtable, which seems strange to me.
If past calcs should be included for any reason wouldn't averaging make more
sense?
I'm open to ways to improve this, but the idea is that the penalty for
overestimating how big the memtable is (frequent flushes) is less severe than
the penalty for underestimating (running out of memory and dying).
> Bogus MemoryMeter liveRatio calculations
> ----------------------------------------
>
> Key: CASSANDRA-4065
> URL: https://issues.apache.org/jira/browse/CASSANDRA-4065
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.0.8
> Reporter: Daniel Doubleday
> Priority: Minor
>
> I get strange cfs.liveRatios.
> A couple of mem meter runs seem to calculate bogus results:
> {noformat}
> Tue 09:14:48 dd@blnrzh045:~$ grep 'setting live ratio to maximum of 64
> instead of' /var/log/cassandra/system.log
> WARN [MemoryMeter:1] 2012-03-20 08:08:07,253 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of Infinity
> WARN [MemoryMeter:1] 2012-03-20 08:08:09,160 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of Infinity
> WARN [MemoryMeter:1] 2012-03-20 08:08:13,274 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of Infinity
> WARN [MemoryMeter:1] 2012-03-20 08:08:22,032 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of Infinity
> WARN [MemoryMeter:1] 2012-03-20 08:12:41,057 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of 67.11787351054079
> WARN [MemoryMeter:1] 2012-03-20 08:13:50,877 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of 112.58547951925435
> WARN [MemoryMeter:1] 2012-03-20 08:15:29,021 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of 193.36945063589877
> WARN [MemoryMeter:1] 2012-03-20 08:17:50,716 Memtable.java (line 193)
> setting live ratio to maximum of 64 instead of 348.45008340969434
> {noformat}
> Because meter runs never decrease liveRatio in Memtable (Which seems strange
> to me. If past calcs should be included for any reason wouldn't averaging
> make more sense?):
> {noformat}
> cfs.liveRatio = Math.max(cfs.liveRatio, newRatio);
> {noformat}
> Memtables are flushed every couple of secs:
> {noformat}
> ColumnFamilyStore.java (line 712) Enqueuing flush of
> Memtable-BlobStore@935814661(1874540/149963200 serialized/live bytes, 202 ops)
> {noformat}
> Even though a saner liveRatio has been calculated after the bogus runs:
> {noformat}
> INFO [MemoryMeter:1] 2012-03-20 08:19:55,934 Memtable.java (line 198)
> CFS(Keyspace='SmeetBlob', ColumnFamily='BlobStore')
> liveRatio is 64.0 (just-counted was 2.97165811895841). calculation took
> 124ms for 58 columns
> {noformat}
--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators:
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira
