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From BRoach <brian.ro...@returnpath.net>
Subject activeMQ 5.1 + activemq-cpp-2.2 openwire transaction problem
Date Sun, 17 Aug 2008 08:23:41 GMT

There seems to be a rather nasty bug having to do with transactions in the
c++ client and openwire.

If you send a large number of messages inside a transaction, and ActiveMQ
runs out of memory, cms::MessageProducer::send() throws an exception (as it
should).

The exception text is: No valid response received for command

The problem is ... the last message sent (the one that caused the exception
to be thrown) gets added to the queue while the others are rolled back. This
is a large problem, as the whole point of transactions is to avoid this sort
of thing.

To summarize: 
- Start sending messages with the session set to SESSION_TRANSACTED
- Fill ActiveMQ memory 
- Receive exception
- The last message sent will be in the queue. All other messages will be
rolled back.

Here's what the debug log looks like:
DEBUG Usage                          - Memory usage change.  from: 2, to: 1
DEBUG AMQMessageStore                - Transacted message add rollback for:
68445488-66bc-c258-0d30-4a1faede93a5:0:1:109, at: offset = 4527877, file =
6, size = 47444, type = 1
DEBUG Usage                          - Memory usage change.  from: 1, to: 0
DEBUG AMQMessageStore                - Transacted message add rollback for:
68445488-66bc-c258-0d30-4a1faede93a5:0:1:110, at: offset = 4575321, file =
6, size = 47439, type = 1
DEBUG TransportConnection            - Connection Stopped: /127.0.0.1:44382
DEBUG AMQMessageStore                - Journalled message add for:
68445488-66bc-c258-0d30-4a1faede93a5:0:1:111, at: offset = 4622760, file =
6, size = 47442, type = 1

As you can see, it adds a message to the queue after the rollback and after
stopping the connection!

Trying to use Stomp rather than openwire creates a whole other set of
problems (at least using the activemq-cpp API). It blocks when you fill the
memory (ok, not so bad) ... but if you kill your client because it's
blocking forever ... activeMQ somehow doesn't lose the socket and you're
completely hosed (you have to restart activeMQ).

I wrote a quick test C client using libstomp rather than activemq-cpp and
can code around this problem using a timeout and some sanity checking ...
but it's a bit of work and I really don't want to have to re-write the
application I've already completed using activemq-cpp.

Thoughts?

Thanks in advance,
Brian Roach

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