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https://issues.apache.org/jira/browse/CASSANDRA-12864?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15628597#comment-15628597
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Benjamin Lerer commented on CASSANDRA-12864:
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{quote}
Also, if it is the expected behavior, I think it's kind of missing the points
of group commit because it can't really control the window size and almost all
of the mutations are committed right after they are issued.
So it can't control the balance between latency and throughput.
{quote}
I have not worked on that part of the code but my understanding is that the
commit log can decide to flush ealier if there is no new incoming mutations
(INSERT, DELETE or UPDATES).
That approach should in fact result in a better throughput for the CommitLog.
I will fix the apache documentation.
> "commitlog_sync_batch_window_in_ms" parameter is not documented correctly
> -------------------------------------------------------------------------
>
> Key: CASSANDRA-12864
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12864
> Project: Cassandra
> Issue Type: Bug
> Components: Documentation and Website
> Reporter: Hiroyuki Yamada
> Assignee: Benjamin Lerer
>
> "commitlog_sync_batch_window_in_ms" doesn't seem to be working at least in
> the latest versions in 2.1.16, 2.2.8 and 3.9.
> Here is the way to reproduce the bug.
> 1. set the following parameters in cassandra.yaml
> * commitlog_sync: batch
> * commitlog_sync_batch_window_in_ms: 10000 (10s)
> 2. issue an insert from cqlsh
> 3. it immediately returns instead of waiting for 10 seconds.
> Please refer to the communication in the mailing list.
> http://www.mail-archive.com/user@cassandra.apache.org/msg49642.html
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