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From "Jonathan Ellis (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-8167) sstablesplit tool can be made much faster with few JVM settings
Date Mon, 27 Oct 2014 17:00:38 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-8167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14185391#comment-14185391
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Jonathan Ellis commented on CASSANDRA-8167:
-------------------------------------------

Do you have a heap dump from the OOM?

> sstablesplit tool can be made much faster with few JVM settings
> ---------------------------------------------------------------
>
>                 Key: CASSANDRA-8167
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-8167
>             Project: Cassandra
>          Issue Type: Improvement
>          Components: Tools
>            Reporter: Nikolai Grigoriev
>            Priority: Trivial
>
> I had to use sstablesplit tool intensively to split some really huge sstables. The tool
is painfully slow as it does compaction in one single thread.
> I have just found that one one of my machines the tool has crashed when I was almost
done with 152Gb sstable (!!!). 
> {code}
>  INFO 16:59:22,342 Writing Memtable-compactions_in_progress@1948660572(0/0 serialized/live
bytes, 1 ops)
>  INFO 16:59:22,352 Completed flushing /cassandra-data/disk1/system/compactions_in_progress/system-compactions_in_progress-jb-79242-Data.db
(42 bytes) for commitlog position ReplayPosition(segmentId=1413904450653, position=69178)
> Exception in thread "main" java.lang.OutOfMemoryError: GC overhead limit exceeded
>         at java.nio.HeapByteBuffer.duplicate(HeapByteBuffer.java:107)
>         at org.apache.cassandra.utils.ByteBufferUtil.readBytes(ByteBufferUtil.java:586)
>         at org.apache.cassandra.utils.ByteBufferUtil.readBytesWithShortLength(ByteBufferUtil.java:596)
>         at org.apache.cassandra.db.marshal.AbstractCompositeType.compare(AbstractCompositeType.java:61)
>         at org.apache.cassandra.db.marshal.AbstractCompositeType.compare(AbstractCompositeType.java:36)
>         at org.apache.cassandra.db.RangeTombstoneList$InOrderTester.isDeleted(RangeTombstoneList.java:751)
>         at org.apache.cassandra.db.DeletionInfo$InOrderTester.isDeleted(DeletionInfo.java:422)
>         at org.apache.cassandra.db.DeletionInfo$InOrderTester.isDeleted(DeletionInfo.java:403)
>         at org.apache.cassandra.db.ColumnFamily.hasIrrelevantData(ColumnFamily.java:489)
>         at org.apache.cassandra.db.compaction.PrecompactedRow.removeDeleted(PrecompactedRow.java:66)
>         at org.apache.cassandra.db.compaction.PrecompactedRow.<init>(PrecompactedRow.java:85)
>         at org.apache.cassandra.db.compaction.CompactionController.getCompactedRow(CompactionController.java:196)
>         at org.apache.cassandra.db.compaction.CompactionIterable$Reducer.getReduced(CompactionIterable.java:74)
>         at org.apache.cassandra.db.compaction.CompactionIterable$Reducer.getReduced(CompactionIterable.java:55)
>         at org.apache.cassandra.utils.MergeIterator$OneToOne.computeNext(MergeIterator.java:204)
>         at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
>         at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
>         at org.apache.cassandra.db.compaction.CompactionTask.runWith(CompactionTask.java:154)
>         at org.apache.cassandra.io.util.DiskAwareRunnable.runMayThrow(DiskAwareRunnable.java:48)
>         at org.apache.cassandra.utils.WrappedRunnable.run(WrappedRunnable.java:28)
>         at org.apache.cassandra.db.compaction.CompactionTask.executeInternal(CompactionTask.java:60)
>         at org.apache.cassandra.db.compaction.AbstractCompactionTask.execute(AbstractCompactionTask.java:59)
>         at org.apache.cassandra.db.compaction.SSTableSplitter.split(SSTableSplitter.java:38)
>         at org.apache.cassandra.tools.StandaloneSplitter.main(StandaloneSplitter.java:150)
> {code}
> This has  triggered my desire to see what memory settings are used for JVM running the
tool...and I have found that it runs with default Java settings (no settings at all).
> I have tried to apply the settings from C* itself and this resulted in over 40% speed
increase. It went from ~5Mb/s to 7Mb/s - from the compressed output perspective. I believe
this is mostly due to concurrent GC. I see my CPU usage has increased to ~200%. But this is
fine, this is an offline tool, the node is down anyway. I know that concurrent GC (at least
something like -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:+CMSParallelRemarkEnabled) normally
improves the performance of even primitive single-threaded heap-intensive Java programs.
> I think it should be acceptable to apply the server JVM settings to this tool.



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