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https://issues.apache.org/activemq/browse/AMQ-2102?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ying updated AMQ-2102:
----------------------
Attachment: AMQ-2102-03102009.patch
Attached AMQ-2102-03102009.patch seems fix all the slave broker out of synch
issue. This is patch is created on activemq 5.2.0 official release tagged
source. sorry that I run a tight schedule and don't have time to patch on
trunk.
One thing missed in this patch is:
{{{
public MessageReference getMessage(MessageId id) throws IOException{
Message msg = this.store.getMessage(id);
return msg;
}
}}}
in org.apache.activemq.broker.region.cursors.QueueStorePrefetch.java
Here is some explaination:
1. MasterBroker.java changes make sure that each command will arrive on the
slave side in the same order. This is necessary because for each specific
message, message itself, dispatch notification and message ack has to come in
the exact order, otherwise, slave out of sync
2. Queue.java if dispatch notification comes and the messages still not in
pending list or pagedIn, it goes to the store to grab the message and add to
the pending then do processMessageDispatchNotification. This is necessary
because that multiple consumers are involved (eg. dispatch notification for
message 201 could come first while only 200 messages on slave side is pagedin
or in the pending list)
Please review it. I urgently need a review of this to make sure the changes are
fine.
A remaining issue which might or might related to this fix:
I see "consumer stop consuming message" when large number of messages is
produced and consumed and I have to restart the broker pair. otherwise, the
brokers seems hanging. do you have any insight what might go wrong?
> 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: AMQ-2102-03102009.patch, 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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