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Posted to commits@cassandra.apache.org by "Yuki Morishita (JIRA)" <ji...@apache.org> on 2012/07/20 00:59:35 UTC
[jira] [Commented] (CASSANDRA-3855) RemoveDeleted dominates
compaction time for large sstable counts
[ https://issues.apache.org/jira/browse/CASSANDRA-3855?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13418759#comment-13418759 ]
Yuki Morishita commented on CASSANDRA-3855:
-------------------------------------------
I ran cpu profile on trunk and 1.1 with LCS and about 1000 sstables. On 1.1 branch, there is no indication of dominating removeDeletedAndOldShards. But for trunk, I noticed that it seemed unnecessary CompactionController#shouldPurge is called inside removeDeletedAndOldShards, where shouldPurge is supposed to be called only when CF has tombstones. So I looked up the code and I'm not sure if this line(https://github.com/apache/cassandra/blob/trunk/src/java/org/apache/cassandra/db/AbstractColumnContainer.java#L201) is correct. If CF is live, returning false for hasIrrelevantData seems right. Sylvain, what do you think?
> RemoveDeleted dominates compaction time for large sstable counts
> ----------------------------------------------------------------
>
> Key: CASSANDRA-3855
> URL: https://issues.apache.org/jira/browse/CASSANDRA-3855
> Project: Cassandra
> Issue Type: Bug
> Components: Core
> Affects Versions: 1.1.0
> Reporter: Stu Hood
> Assignee: Yuki Morishita
> Labels: compaction, deletes, leveled
> Attachments: with-cleaning-java.hprof.txt
>
>
> With very large numbers of sstables (2000+ generated by a `bin/stress -n 100,000,000` run with LeveledCompactionStrategy), PrecompactedRow.removeDeletedAndOldShards dominates compaction runtime, such that commenting it out takes compaction throughput from 200KB/s to 12MB/s.
> Stack attached.
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