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https://issues.apache.org/jira/browse/CASSANDRA-6692?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13906400#comment-13906400
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Aleksey Yeschenko commented on CASSANDRA-6692:
----------------------------------------------
This seems to have broken a bunch of tests (getting NPE from isLeaf()).
For example,
{noformat}
[junit] Testcase:
testIndexUpdate(org.apache.cassandra.db.ColumnFamilyStoreTest): Caused an
ERROR
[junit] null
[junit] java.lang.NullPointerException
[junit] at org.apache.cassandra.utils.btree.BTree.isLeaf(BTree.java:302)
[junit] at
org.apache.cassandra.utils.btree.NodeBuilder.update(NodeBuilder.java:131)
[junit] at
org.apache.cassandra.utils.btree.Builder.update(Builder.java:74)
[junit] at org.apache.cassandra.utils.btree.BTree.update(BTree.java:157)
[junit] at
org.apache.cassandra.db.AtomicBTreeColumns.addAllWithSizeDelta(AtomicBTreeColumns.java:254)
[junit] at org.apache.cassandra.db.Memtable.put(Memtable.java:195)
[junit] at
org.apache.cassandra.db.ColumnFamilyStore.apply(ColumnFamilyStore.java:1096)
[junit] at org.apache.cassandra.db.Keyspace.apply(Keyspace.java:370)
[junit] at org.apache.cassandra.db.Keyspace.apply(Keyspace.java:328)
[junit] at org.apache.cassandra.db.Mutation.apply(Mutation.java:205)
[junit] at
org.apache.cassandra.db.ColumnFamilyStoreTest.testIndexUpdate(ColumnFamilyStoreTest.java:389)
{noformat}
> AtomicBTreeColumns Improvements
> -------------------------------
>
> Key: CASSANDRA-6692
> URL: https://issues.apache.org/jira/browse/CASSANDRA-6692
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Assignee: Benedict
> Priority: Minor
> Labels: easyfix, performance
> Fix For: 2.1
>
>
> There are two improvements to make to the BTree code that should help:
> 1) It turns out Stack Allocation is more rubbish than we had hoped, and so
> the fast route actually allocates garbage. It's unlikely this reduces
> throughput, but the increased young-gen pressure is probably unwelcome. I
> propose to remove the fast route for now.
> 2) It is not uncommon to race to perform an update, so that the new values
> are actually out-of-date when we come to modify the tree. In this case the
> update should recognise that the original (portion of) the tree has not been
> modified, and simply return it, without allocating a new one.
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