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https://issues.apache.org/activemq/browse/AMQ-2102?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=50234#action_50234
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Gary Tully commented on AMQ-2102:
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sorry, my patch is still a bit of a work in progress. I was using this jira as
a shared holder. For the cce,{code} private QueueMessageReference
getMatchingMessage(MessageDispatchNotification messageDispatchNotification)
throws Exception {code} needs to return a QueueMessageReference.
Add the following to get it to work better. I still need to validate that the
dispatch that that happens here is correct w.r.t a normal dispatch. I have run
it by applying the patch to trunk, so only with your changes to MasterBroker,
ignoring the MasterBroker changes in the patch. With 30000 messages I still get
errors, but of a different kind. More work needed.
{code}
if (message == null) {
synchronized (messages) {
try {
messages.reset();
while (messages.hasNext()) {
MessageReference node = messages.next();
+ node.incrementReferenceCount();
+ messages.remove();
if (messageId.equals(node.getMessageId())) {
+ message =
this.createMessageReference(node.getMessage());
{code}
> Master/slave out of sync with multiple consumers
> ------------------------------------------------
>
> Key: AMQ-2102
> URL: https://issues.apache.org/activemq/browse/AMQ-2102
> Project: ActiveMQ
> Issue Type: Bug
> Components: Broker
> Affects Versions: 5.2.0
> Reporter: Dan James
> Assignee: Gary Tully
> Attachments: master.xml, MasterSlaveBug.java, MasterSlavePatch.patch,
> slave.xml, slaveDispatchOnNotification.patch
>
>
> 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.
> Master and slave configurations along with MasterSlaveBug.java are attached
> to this issue.
> Start master and slave brokers:
> activemq xbean:master.xml
> activemq xbean:slave.xml
> Run with (only one consumer, the bug does not appear):
> java -classpath .:activemq-all-5.2.0.jar MasterSlaveBug 1
> Run with (sixteen consumers, the bug does appear):
> java -classpath .:activemq-all-5.2.0.jar MasterSlaveBug 16
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