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https://issues.apache.org/jira/browse/DERBY-6879?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15355255#comment-15355255
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Brett Bergquist commented on DERBY-6879:
----------------------------------------
My thoughts about always synchronizing on the connection first will not work.
It does fix the immediate problem, but now when XA transaction is going to be
to be timed out, the "cancel" waits for the connection to be able to be
synchronized. If the connection is executing a long running SQL statement,
then the cancel actually waits for the completion before the "cancel" attempts
to cancel. So while it does solve the deadlock, it introduces another anomaly
and as such is not the correct solution.
> Engine deadlock between XA timeout handling and cleanupOnError
> --------------------------------------------------------------
>
> Key: DERBY-6879
> URL: https://issues.apache.org/jira/browse/DERBY-6879
> Project: Derby
> Issue Type: Bug
> Components: Services
> Affects Versions: 10.10.2.0
> Environment: Solaris 10.5 on Oracle M5000
> Reporter: Brett Bergquist
> Attachments: derby-6879-test.diff
>
>
> Deadlock between XA timer cleanup task and the ContextManager.cleanupOnError
> Found one Java-level deadlock:
> =============================
> "DRDAConnThread_34":
> waiting to lock monitor 0x0000000104b14d18 (object 0xfffffffd9090f058, a
> org.apache.derby.jdbc.XATransactionState),
> which is held by "Timer-0"
> "Timer-0":
> waiting to lock monitor 0x00000001038b96e8 (object 0xfffffffd9090d8b0, a
> org.apache.derby.impl.jdbc.EmbedConnection40),
> which is held by "DRDAConnThread_34"
>
> Java stack information for the threads listed above:
> ===================================================
> "DRDAConnThread_34":
> at org.apache.derby.jdbc.XATransactionState.cleanupOnError(Unknown
> Source)
> - waiting to lock <0xfffffffd9090f058> (a
> org.apache.derby.jdbc.XATransactionState)
> at
> org.apache.derby.iapi.services.context.ContextManager.cleanupOnError(Unknown
> Source)
> at
> org.apache.derby.impl.jdbc.TransactionResourceImpl.cleanupOnError(Unknown
> Source)
> at
> org.apache.derby.impl.jdbc.TransactionResourceImpl.handleException(Unknown
> Source)
> at org.apache.derby.impl.jdbc.EmbedConnection.handleException(Unknown
> Source)
> at org.apache.derby.impl.jdbc.ConnectionChild.handleException(Unknown
> Source)
> at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(Unknown
> Source)
> - locked <0xfffffffd9090d8b0> (a
> org.apache.derby.impl.jdbc.EmbedConnection40)
> at
> org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Unknown
> Source)
> at org.apache.derby.impl.jdbc.EmbedPreparedStatement.execute(Unknown
> Source)
> at org.apache.derby.iapi.jdbc.BrokeredPreparedStatement.execute(Unknown
> Source)
> at org.apache.derby.impl.drda.DRDAStatement.execute(Unknown Source)
> at
> org.apache.derby.impl.drda.DRDAConnThread.parseEXCSQLSTTobjects(Unknown
> Source)
> at org.apache.derby.impl.drda.DRDAConnThread.parseEXCSQLSTT(Unknown
> Source)
> at org.apache.derby.impl.drda.DRDAConnThread.processCommands(Unknown
> Source)
> at org.apache.derby.impl.drda.DRDAConnThread.run(Unknown Source)
> "Timer-0":
> at org.apache.derby.impl.jdbc.EmbedConnection.xa_rollback(Unknown Source)
> - waiting to lock <0xfffffffd9090d8b0> (a
> org.apache.derby.impl.jdbc.EmbedConnection40)
> at org.apache.derby.jdbc.XATransactionState.cancel(Unknown Source)
> - locked <0xfffffffd9090f058> (a
> org.apache.derby.jdbc.XATransactionState)
> at
> org.apache.derby.jdbc.XATransactionState$CancelXATransactionTask.run(Unknown
> Source)
> at java.util.TimerThread.mainLoop(Timer.java:555)
> at java.util.TimerThread.run(Timer.java:505)
>
> Found 1 deadlock.
> This deadlock caused Derby to create 18000 transaction recovery logs because
> of the XA transaction that did not cleanup in the timeout. Rebooting the
> system would cause a 50 hour boot up time to process the transaction logs so
> recovery had to be done by going to a backup database before the issue
> occurred.
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