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Date: Tue, 15 Apr 2014 16:46:20 +0000 (UTC)
From: "Benedict (JIRA)" <jira@apache.org>
To: commits@cassandra.apache.org
Message-ID: <JIRA.12704274.1396020309633.118259.1397580380459@arcas>
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Subject: [jira] [Commented] (CASSANDRA-6949) Performance regression in
 tombstone heavy workloads
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    [ https://issues.apache.org/jira/browse/CASSANDRA-6949?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13969716#comment-13969716 ] 

Benedict commented on CASSANDRA-6949:
-------------------------------------

It's worth pointing out that a sensible intersection implementation over two ordered sets can be quite efficient and a fairly low computational burden, which is possibly a good middle ground. But if there's no real risk to getting rid of it, that's probably best.

> Performance regression in tombstone heavy workloads
> ---------------------------------------------------
>
>                 Key: CASSANDRA-6949
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6949
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Jeremiah Jordan
>            Assignee: Sam Tunnicliffe
>         Attachments: 0001-Remove-expansion-of-RangeTombstones-to-delete-from-2.patch, 6949.txt
>
>
> CASSANDRA-5614 causes a huge performance regression in tombstone heavy workloads.  The isDeleted checks here cause a huge CPU overhead: https://github.com/apache/cassandra/blob/cassandra-2.0/src/java/org/apache/cassandra/db/AtomicSortedColumns.java#L189-L196
> An insert workload which does perfectly fine on 1.2, pegs CPU use at 100% on 2.0, with all of the mutation threads sitting in that loop.  For example:
> {noformat}
> "MutationStage:20" daemon prio=10 tid=0x00007fb1c4c72800 nid=0x2249 runnable [0x00007fb1b0330000]
>    java.lang.Thread.State: RUNNABLE
> at org.apache.cassandra.db.marshal.BytesType.bytesCompare(BytesType.java:45)
> at org.apache.cassandra.db.marshal.UTF8Type.compare(UTF8Type.java:34)
> at org.apache.cassandra.db.marshal.UTF8Type.compare(UTF8Type.java:26)
> at org.apache.cassandra.db.marshal.AbstractType.compareCollectionMembers(AbstractType.java:267)
> at org.apache.cassandra.db.marshal.AbstractCompositeType.compare(AbstractCompositeType.java:85)
> at org.apache.cassandra.db.marshal.AbstractCompositeType.compare(AbstractCompositeType.java:35)
> at org.apache.cassandra.db.RangeTombstoneList.searchInternal(RangeTombstoneList.java:253)
> at org.apache.cassandra.db.RangeTombstoneList.isDeleted(RangeTombstoneList.java:210)
> at org.apache.cassandra.db.DeletionInfo.isDeleted(DeletionInfo.java:136)
> at org.apache.cassandra.db.DeletionInfo.isDeleted(DeletionInfo.java:123)
> at org.apache.cassandra.db.AtomicSortedColumns.addAllWithSizeDelta(AtomicSortedColumns.java:193)
> at org.apache.cassandra.db.Memtable.resolve(Memtable.java:194)
> at org.apache.cassandra.db.Memtable.put(Memtable.java:158)
> at org.apache.cassandra.db.ColumnFamilyStore.apply(ColumnFamilyStore.java:890)
> at org.apache.cassandra.db.Keyspace.apply(Keyspace.java:368)
> at org.apache.cassandra.db.Keyspace.apply(Keyspace.java:333)
> at org.apache.cassandra.db.RowMutation.apply(RowMutation.java:201)
> at org.apache.cassandra.db.RowMutationVerbHandler.doVerb(RowMutationVerbHandler.java:56)
> at org.apache.cassandra.net.MessageDeliveryTask.run(MessageDeliveryTask.java:60)
> at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
> at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
> at java.lang.Thread.run(Thread.java:744)
> {noformat}


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