[
https://issues.apache.org/jira/browse/CASSANDRA-11623?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15253910#comment-15253910
]
Marcus Eriksson commented on CASSANDRA-11623:
---------------------------------------------
Nice catch!
It looks like we could just use the
[chunkOffset|https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/io/compress/CompressedSequentialWriter.java#L143]
directly instead though? Old getOnDiskFilePointer() should always be [exactly
the
same|https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/io/compress/CompressedSequentialWriter.java#L104]
as the chunkOffset
> Compactions w/ Short Rows Spending Time in getOnDiskFilePointer
> ---------------------------------------------------------------
>
> Key: CASSANDRA-11623
> URL: https://issues.apache.org/jira/browse/CASSANDRA-11623
> Project: Cassandra
> Issue Type: Improvement
> Reporter: Tom Petracca
> Priority: Minor
> Attachments: compactiontask_profile.png
>
>
> Been doing some performance tuning and profiling of my cassandra cluster and
> noticed that compaction speeds for my tables that I know to have very short
> rows were going particularly slowly. Profiling shows a ton of time being
> spent in BigTableWriter.getOnDiskFilePointer(), and attaching strace to a
> CompactionTask shows that a majority of time is being spent lseek (called by
> getOnDiskFilePointer), and not read or write.
> Going deeper it looks like we call getOnDiskFilePointer each row (sometimes
> multiple times per row) in order to see if we've reached our expected sstable
> size and should start a new writer. This is pretty unnecessary.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
