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https://issues.jboss.org/browse/JBTM-1865?page=com.atlassian.jira.plugin....
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Mark Little commented on JBTM-1865:
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"It's 2PC and the XAResource has already guaranteed to commit the
transaction." If we lived in the world of the strict 2PC protocol then you would be
right. However, no transaction manager standard or implementation since the 1960's has
been able to live in that world, since strict 2PC is a blocking protocol. As a result,
heuristics were introduced and any resource that has prepared can still go back on that
choice between prepare and being told what to do by the coordinator. The only thing it has
to do is remember this autonomous decision so it can report it to the coordinator
eventually.
This is all documented at length in various standards and books. We also have quite a few
articles and videos on the
JBoss.org site as well as in the JBoss transactions team's
blog. I recommend you check them out if you need further clarification.
Transaction reported to be rolled back, although committed with one
participant
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Key: JBTM-1865
URL:
https://issues.jboss.org/browse/JBTM-1865
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
While testing recovery and transaction failures we came across
two related issues, the test scenario is almost the same, I'll file the second issue
shortly and update this ticket accordingly.
Scenario:
2 enlisted XAResources (one for each database used by the test),
The prepare phase is successful.
We crash the first 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.
But now things go awry:
1. There is a XAResource.rollback() issued to the second XAResource.
2. The client receives a EJBTransactionRolledbackException, although
one branch has been completed.
Note, that our database does not support heuristical completion of a branch at all, i.e.
there should be no Heuristic* exception be thrown either.
The correct behavior is, to report the transaction as success to the client, commit all
branches. All XAResources which failed during XAResource.commit() are supposed to be
recovered in future.
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