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From "Kathey Marsden (JIRA)" <j...@apache.org>
Subject [jira] Commented: (DERBY-3980) Conflicting select then update with REPEATABLE_READ gives lock timeout instead of deadlock
Date Tue, 16 Dec 2008 21:14:44 GMT

    [ https://issues.apache.org/jira/browse/DERBY-3980?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12657165#action_12657165

Kathey Marsden commented on DERBY-3980:

Thanks Knut for looking at the patch.  I committed  revision 727147 for the changes you recommended.
 The test for deadlock detection I checked in was Derby3980DeadlockTest.  That test currently
fails with a lock timeout, so is not part of the suite.

I added LiveLockTest because Mike suggested that we add a test for the live lock scenario
as part of this issue, so we make sure we don't regress. Perhaps it would have been clearer
to open a separate issue.  I hope I understood live lock correctly and that's what's being
tested with LiveLockTest.  If not,  I'll try to make another shot at it when I get back from
holiday in a few weeks time.  Hopefully  the mysteries of Deadlock.look() will be unlocked
during that time and this issue can be resolved. If so the test Derby3980DeadlockTest should
be enabled.


> Conflicting select then update with REPEATABLE_READ gives lock timeout instead of deadlock
> ------------------------------------------------------------------------------------------
>                 Key: DERBY-3980
>                 URL: https://issues.apache.org/jira/browse/DERBY-3980
>             Project: Derby
>          Issue Type: Bug
>          Components: Store
>    Affects Versions:,,,,
>            Reporter: Kathey Marsden
>         Attachments: derby-3980_javadoc_and_test_diff.txt, derby.log, derby.log.10_1,
javacore.20081209.092827.9800.txt, LiveLockTest_diff.txt, LockTimeoutWithInserts.java, TryTimeout.java,
TryTimeout2.java, TryTimeout2.out.10_1.deadlock, TryTimeout2.out.10_1.deadlock, TryTimeout2.out.10_1.locktimeout,
> The attached program TryTimeout.java should detect a deadlock but instead throws a lock
timeout exception.  The program has two threads that attempt:
> 	    threadConnection.setAutoCommit(false);
> 	    /* set isolation level to repeatable read */
> 	    threadConnection.setTransactionIsolation(Connection.TRANSACTION_REPEATABLE_READ);
> 	    ResultSet rs = stmt.executeQuery("select * from t where i = 456");
> 	    while (rs.next());
> 	    stmt.executeUpdate("update t set i = 456 where i = 456");
> 	    threadConnection.commit();
> This gives SQLState 40001 (deadlock) with DB2 but a lock timeout with Derby.

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