Jose Alvarado created AMQNET-503:
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Summary: DTC Transactions do not respect rollbacks consistently
leading to duplicated messages
Key: AMQNET-503
URL: https://issues.apache.org/jira/browse/AMQNET-503
Project: ActiveMQ .Net
Issue Type: Bug
Components: ActiveMQ
Reporter: Jose Alvarado
Assignee: Jim Gomes
In certain circumstances, rollback does not work properly, as a result
duplicate messages are generated from normal DTC operations. The circumstances
under which this issues occurs are:
- DTC transaction initiated, but fails to commit;
- Another DTC transaction initiated and successfully commits;
- When a transaction is roll backed and committed on retry;
As a result the number of messages sent is larger to the number of messages
received by the target broker. Some of the messages are not roll backed when it
fails and they get sent again when committed on retry.
This issue has been raised in Jira as issues 413 and 472:
https://issues.apache.org/jira/browse/AMQNET-413
https://issues.apache.org/jira/browse/AMQNET-472
Analysing the code we realised that these two issues above are similar, and
they have the same cause. We have therefore developed a patch based on feedback
and unit tests provided by those two issues, where we fix the problem and we
pass all existing unit tests. The changes modify only code related to DTC, and
it was developed in .NET 2.0 as per the requirements for 413/472
The fix implements the solution suggested in the patch for issue 472 where some
lock conditions were missing. In addition we have added a condition where we
will not lock the transaction whenever a distributed transaction occurs. The
DtcWaitHandle.WaitOne causes DTC transactions involving a database or XA
transaction to fail unit testing.
The patch was extensively tested with over a 1000 messages (1K, 1.5K, 10K,
100K, 1M) using two brokers across different servers to guarantee distributed
transactions. Testing also included different message sizes, infrastructure
setup, databases, and message content verification to validate its integrity
and ensure messages were not duplicated.
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