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Posted to commits@cassandra.apache.org by "Wei Deng (JIRA)" <ji...@apache.org> on 2016/07/21 08:46:20 UTC
[jira] [Updated] (CASSANDRA-6496) Endless L0 LCS compactions
[ https://issues.apache.org/jira/browse/CASSANDRA-6496?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Wei Deng updated CASSANDRA-6496:
--------------------------------
Labels: compaction lcs (was: compaction)
> Endless L0 LCS compactions
> --------------------------
>
> Key: CASSANDRA-6496
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6496
> Project: Cassandra
> Issue Type: Bug
> Environment: Cassandra 2.0.3, Linux, 6 nodes, 5 disks per node
> Reporter: Nikolai Grigoriev
> Assignee: Jonathan Ellis
> Labels: compaction, lcs
> Fix For: 2.0.4
>
> Attachments: 6496.txt, system.log.1.gz, system.log.gz
>
>
> I have first described the problem here: http://stackoverflow.com/questions/20589324/cassandra-2-0-3-endless-compactions-with-no-traffic
> I think I have really abused my system with the traffic (mix of reads, heavy updates and some deletes). Now after stopping the traffic I see the compactions that are going on endlessly for over 4 days.
> For a specific CF I have about 4700 sstable data files right now. The compaction estimates are logged as "[3312, 4, 0, 0, 0, 0, 0, 0, 0]". sstable_size_in_mb=256. 3214 files are about 256Mb (+/1 few megs), other files are smaller or much smaller than that. No sstables are larger than 256Mb. What I observe is that LCS picks 32 sstables from L0 and compacts them into 32 sstables of approximately the same size. So, what my system is doing for last 4 days (no traffic at all) is compacting groups of 32 sstables into groups of 32 sstables without any changes. Seems like a bug to me regardless of what did I do to get the system into this state...
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