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https://issues.apache.org/jira/browse/CASSANDRA-12763?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15562717#comment-15562717
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Jeremy Hanna commented on CASSANDRA-12763:
------------------------------------------
As an aside, you may want to determine why you have a lot of small sstables in
the first place. One common cause is when people change the number of flush
writers but don't change the memtable cleanup threshold. So it flushes much
more frequently, resulting in lots of small sstables. Granted we want to
improve the handling of a lot of small sstables, but flushing larger sstables
will help avoid the problem.
> Compaction performance issues when a table has a lot of sstables
> ----------------------------------------------------------------
>
> Key: CASSANDRA-12763
> URL: https://issues.apache.org/jira/browse/CASSANDRA-12763
> Project: Cassandra
> Issue Type: Bug
> Components: Compaction
> Reporter: Tom van der Woerdt
>
> An issue with a script flooded my cluster with sstables. There is now a table
> with 100k sstables, all on the order of KBytes, and it's taking a long time
> (ETA 20 days) to compact, even though the table is only ~30GB.
> Stack trace :
> {noformat}
> "CompactionExecutor:269" #7536 daemon prio=1 os_prio=4 tid=0x00007f4acd40fc00
> nid=0x14f8 runnable [0x00007f4798436000]
> java.lang.Thread.State: RUNNABLE
> at java.io.UnixFileSystem.list(Native Method)
> at java.io.File.list(File.java:1122)
> at java.io.File.listFiles(File.java:1248)
> at
> org.apache.cassandra.db.lifecycle.LogRecord.getExistingFiles(LogRecord.java:268)
> at org.apache.cassandra.db.lifecycle.LogRecord.make(LogRecord.java:150)
> at
> org.apache.cassandra.db.lifecycle.LogFile.makeRecord(LogFile.java:293)
> at org.apache.cassandra.db.lifecycle.LogFile.add(LogFile.java:283)
> at
> org.apache.cassandra.db.lifecycle.LogTransaction.obsoleted(LogTransaction.java:158)
> at
> org.apache.cassandra.db.lifecycle.Helpers.prepareForObsoletion(Helpers.java:134)
> at
> org.apache.cassandra.db.lifecycle.LifecycleTransaction.doPrepare(LifecycleTransaction.java:193)
> at
> org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.prepareToCommit(Transactional.java:173)
> at
> org.apache.cassandra.io.sstable.SSTableRewriter.doPrepare(SSTableRewriter.java:376)
> at
> org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.prepareToCommit(Transactional.java:173)
> at
> org.apache.cassandra.db.compaction.writers.CompactionAwareWriter.doPrepare(CompactionAwareWriter.java:84)
> at
> org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.prepareToCommit(Transactional.java:173)
> at
> org.apache.cassandra.utils.concurrent.Transactional$AbstractTransactional.finish(Transactional.java:184)
> at
> org.apache.cassandra.db.compaction.writers.CompactionAwareWriter.finish(CompactionAwareWriter.java:94)
> at
> org.apache.cassandra.db.compaction.CompactionTask.runMayThrow(CompactionTask.java:194)
> at
> org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:28)
> at
> org.apache.cassandra.db.compaction.CompactionTask.executeInternal(CompactionTask.java:78)
> at
> org.apache.cassandra.db.compaction.AbstractCompactionTask.execute(AbstractCompactionTask.java:61)
> at
> org.apache.cassandra.db.compaction.CompactionManager$BackgroundCompactionCandidate.run(CompactionManager.java:263)
> at
> java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
> at java.util.concurrent.FutureTask.run(FutureTask.java:266)
> at
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
> at java.lang.Thread.run(Thread.java:745)
> {noformat}
> listFiles is being called over and over, apparently scaling with the number
> of files in the compaction.
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