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From "Benedict (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (CASSANDRA-6943) UpdateFunction.abortEarly can cause BTree.update to leave its Builder in a bad state, which affects future operations
Date Fri, 28 Mar 2014 14:25:16 GMT

    [ https://issues.apache.org/jira/browse/CASSANDRA-6943?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13950765#comment-13950765
] 

Benedict commented on CASSANDRA-6943:
-------------------------------------

For anyone looking for a little more information: this problem would be hit when inserting
a larger number of records into an existing record than were currently present in that record
(excluding empty records) causing a over-spill into a new parent node, after which there was
a competing update to the underlying record, and the update that overspilled aborted before
finishing the construction of its replacement btree. In this case it did not clear the state
of the builder for the spilled-over parent, as it only visited all those from its original
root/parent down to reset the state (it would ascend to the real parent on finishing construction),
so that when the next update finished it included this old partially constructed parent, resulting
in a malformed btree.

The simple solution is to always go up resetting all parents on completion, as well as down

> UpdateFunction.abortEarly can cause BTree.update to leave its Builder in a bad state,
which affects future operations
> ---------------------------------------------------------------------------------------------------------------------
>
>                 Key: CASSANDRA-6943
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-6943
>             Project: Cassandra
>          Issue Type: Bug
>            Reporter: Russ Hatch
>            Assignee: Benedict
>             Fix For: 2.1 beta2
>
>         Attachments: 6943.2.txt, 6943.txt, node4.log, node4_jstack.log, node5.log, node5_jstack.log,
node6.log, node6_jstack.log, node7.log, node7_jstack.log, screenshot.png, screenshot2.png,
stress_jstack.log
>
>
> Running performance scenarios I have seen this characteristic drop in performance happen
several times. A similar effect was reproduced in another test cluster. Operations eventually
come to a standstill.
> !screenshot.png!
> !screenshot2.png!



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