[jbossts-issues] [JBoss JIRA] (JBTM-1866) HeuristicMixedException reported to client, although backends don't support heuristic completion

Mark Little (JIRA) jira-events at lists.jboss.org
Wed Jul 31 08:43:26 EDT 2013


    [ https://issues.jboss.org/browse/JBTM-1866?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12794186#comment-12794186 ] 

Mark Little commented on JBTM-1866:
-----------------------------------

It does not contradict what Phil and the others wrote in their book. Please go and re-read heuristics and why they were introduced. Also take this to the transactions forum. Check out http://qconlondon.com/dl/qcon-london-2010/slides/MarkLittle_TransactionsOverUsedOrJustMisunderstood.pdf as you may find that useful.

And finally I will repeat: just because a participant says it has prepared DOES NOT MEAN THE TRANSACTION WILL COMMIT. If that were the case then we wouldn't need the 2nd phase of the 2PC protocol because apparently all of the prepared resources will commit and somehow (maybe through ESP?) know that all other resources will also commit.
                
> HeuristicMixedException reported to client, although backends don't support heuristic completion
> ------------------------------------------------------------------------------------------------
>
>                 Key: JBTM-1866
>                 URL: https://issues.jboss.org/browse/JBTM-1866
>             Project: JBoss Transaction Manager
>          Issue Type: Bug
>      Security Level: Public(Everyone can see) 
>          Components: Transaction Core
>    Affects Versions: 4.17.4
>            Reporter: Christian von Kutzleben
>            Assignee: Tom Jenkinson
>
> this bug is related to:
> https://issues.jboss.org/browse/JBTM-1865
> While testing recovery and transaction failures we came across
> two related issues, the test scenario is almost the same, the other
> issue is filed as JBTM-1865
> Scenario: 
> 2 enlisted XAResources (one for each database used by the test),
> The prepare phase is successful.
> We crash the second database server during the XAResource.commit invocation,
> _after_ it has committed it's branch, right before the control flow would return to the XAResource (which as a result throws a XAException.XA_RBCOMMFAIL).
> The TM can not know at this point in time, whether the database successfully committed the transaction or not. In this particular case, all changes have been committed.
> By definition of the 2PC protocol, the transaction should be considered as "to be committed", because the prepare phase has ended successfully.
> The first branch was successfully committed (as it should be spec.)
> But now things go awry:
> 1. The client receives a HeuristicMixedException, although the backend
> does not support heuristic completion at all, i.e. there should be no Heuristic* exception be thrown
> The correct behavior is, to report the transaction as success to the client, commit all other branches. All XAResources which failed during XAResource.commit() are supposed to be recovered in future.

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