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https://issues.apache.org/jira/browse/CASSANDRA-8167?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15537171#comment-15537171
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Jeremiah Jordan commented on CASSANDRA-8167:
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The "offline" part is that they require your node to be "offline" to run them.
I'm not sure about just using the cassandra-env.sh settings in those tools
though, I would suggest rather that we have a cassandra-tools-env.sh or
similar. Though maybe it is OK for all the truly offline tools, we just need
to be careful here as if someone has a 32 GB heap size on a node which has 64
GB total, we don't want to OOM the node because they ran a tool and it tried to
take up all the free ram.
> 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
> Assignee: Yuki Morishita
> 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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