Hi Dan, can you create an issue for this and attach your test program to it?
Regards -- Dejan Bosanac Open Source Integration - http://fusesource.com/ ActiveMQ in Action - http://www.manning.com/snyder/ Blog - http://www.nighttale.net On Fri, Feb 6, 2009 at 3:42 PM, Dan James <dja...@verisign.com> wrote: > > I'm seeing exceptions like this in a simple master/slave setup: > > ERROR Service - Async error occurred: > javax.jms.JMSException: Slave broker out of sync with master: Dispatched > message (ID:DUL1SJAMES-L2-1231-1233929569359-0:4:1:1:207) was not in the > pending list for MasterSlaveBug > javax.jms.JMSException: Slave broker out of sync with master: Dispatched > message (ID:DUL1SJAMES-L2-1231-1233929569359-0:4:1:1:207) was not in the > pending list for MasterSlaveBug > > The problem only happens when there are multiple consumers listening to the > queue, and is more likely to occur as there are more consumers listening. > I've written a test program that demonstrates the problem. > > I start the master and slave with an empty data directory and let them both > startup and settle. Then start the test program. The test program creates > a specified number of consumers, and then starts queuing 256 messages. The > consumers process the message by sending a reply. The producer counts the > replies. Both consumers and the producer see all the messages, but with > multiple consumers it is very likely that the error above will occur and > several of the messages will still be queued on the slave. > > While debugging through the activemq code, I noticed that both the master > and the slave dispatch the message to a consumer's pending list > independently. In other words, it is possible that the master will add the > message to consumer A's pending list and the slave will add the message to > consumer B's pending list. Once the message has been processed by consumer > A, the master sends a message to the slaving which specifies consumer A so > that the slave can remove the message. The slave looks on its copy of > consumer A's pending list and cannot find the message. As a result, it > throws this exception and the message stays stuck on consumer B's pending > list on the slave. > -- > View this message in context: > http://www.nabble.com/Master-slave-out-of-sync-with-multiple-consumers-tp21873754p21873754.html > Sent from the ActiveMQ - User mailing list archive at Nabble.com. > >
