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https://issues.apache.org/jira/browse/CASSANDRA-6079?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13776450#comment-13776450
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Oleg Anastasyev commented on CASSANDRA-6079:
--------------------------------------------
Well, I did some quick test. As i suspected there is no measurable performance
impact on this.
3 node cluster, RF=3, separated client, writing batches of 3 inserts each to 3
different CFs. 8 core (not so) recent iron servers.
(no batches were replayed actually, so this pure common case).
I measured this for 1 hour run in both cases.
Here is performance WITH wait on get():
avg 3052 batches/sec, st deviance 131
WITHOUT waiting in get()
avg 3030 per sec, deviance 106
> Memtables flush is delayed when having a lot of batchlog activity, making
> node OOM
> ----------------------------------------------------------------------------------
>
> Key: CASSANDRA-6079
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6079
> Project: Cassandra
> Issue Type: Bug
> Reporter: Oleg Anastasyev
> Assignee: Oleg Anastasyev
> Priority: Minor
> Fix For: 1.2.11, 2.0.2
>
> Attachments: NoWaitBatchlogCompaction.diff
>
>
> Both MeteredFlusher and BatchlogManager share the same OptionalTasks thread.
> So, when batchlog manager processes its tasks no flushes can occur. Even
> more, batchlog manager waits for batchlog CF compaction to finish.
> On a lot of batchlog activity this prevents memtables from flush for a long
> time, making the node OOM.
> Fixed this by moving batchlog to its own thread and not waiting for batchlog
> compaction to finish.
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