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From "Andrew May (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (AMQ-4720) Messages lost after fail-back of a network connector using priorityBackup=true - reason is that remote broker isn't checking producerID & is rejecting because of duplicate producerSequence
Date Thu, 12 Sep 2013 09:56:54 GMT

    [ https://issues.apache.org/jira/browse/AMQ-4720?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13765313#comment-13765313
] 

Andrew May commented on AMQ-4720:
---------------------------------

I've tried using the masterslave: discovery agent (instead of "static:(failover:") but this
agent doesn't seem to support fail-back to a priority connection.
                
> Messages lost after fail-back of a network connector using priorityBackup=true - reason
is that remote broker isn't checking producerID & is rejecting because of duplicate producerSequence
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: AMQ-4720
>                 URL: https://issues.apache.org/jira/browse/AMQ-4720
>             Project: ActiveMQ
>          Issue Type: Bug
>          Components: Broker, Connector
>    Affects Versions: 5.8.0
>         Environment: Only tested on Windows 7 Enterprise x64.
>            Reporter: Andrew May
>              Labels: failback, failover, networkBridge,, networkConnector
>         Attachments: amq1.log, amq1.xml, amq2.log, amq2.xml, amq3.log, amq3.xml
>
>
> Summary of problem:
> -------------------
> If a static failover network connector is setup to connect to 2 other brokers & to
fail-back to a priority broker; messages can be lost after fail-back because the remote broker
deletes them due to duplicate producer-sequence numbers even though the producer-id has changed.
> My suspicion is that the remote broker doesn't recognise that the re-established connection
is a network connection & so doesn't check producer-id.
> Test-harness setup:
> -------------------
> Using ActiveMQ 5.8.0 binary download.
> Only changes are to logging settings & to the configuration file.
> 3 brokers ("amq1", "amq2", "amq3"), all brokers running on localhost.
> Each uses their own config file (amq1.xml, amq2.xml, amq3.xml)
> Broker amq1 has a failover duplex connection to amq2.
> Broker amq3 has a duplex failover connection to both amq1 + amq2, it is configured to
always try to connect to amq1 first ("randomize=false") and to fail-back to amq1 if it comes
back online ("priorityBackup=true")
> Consumer connects to broker amq1
> Producer connects to broker amq3
> Test-harness sender application creates a new session each time it is run & sends
a set of messages.
> The sending session is not transacted & is set to auto-acknowledge.
> Messages are sent with persistent delivery mode.
> Messages are on queue "MyQueue"
> Test script:
> ------------
> Start all 3 brokers.
> Broker amq3 establishes a connection to amq1.
> Broker amq1 establishes a connection to amq2.
> Consumer connects to amq2 & starts consuming queue "MyQueue".
> Producer connects to amq3 & sends 10 messages on queue "MyQueue" - these are all
passed on to broker amq1 which forwards them to amq2 where they are delivered to the consumer.
> Producer connects to amq3 & sends 10 messages on queue "MyQueue" - these are all
delivered as before - N.B. producerID is different as this is a new connection.
> Broker amq1 is shut down.
> Broker amq3 fails-over to connect to amq2.
> Producer connects to amq3 & sends 10 messages on queue "MyQueue" - these are all
passed directly to amq2 where they are delivered to the consumer - (as before, the producer-id
has changed).
> Producer connects to amq3 & sends 10 messages on queue "MyQueue" - these are delivered
as before.
> Broker amq1 is restarted 
> Broker amq1 re-establishes its connection to amq2.
> Broker amq3 notices that amq1 is available & fails-back to it.
>     - Broker amq3 closes its connection to amq2
>     - Broker amq3 starts a new connection to amq1
> Producer connects to amq3 & sends 10 messages on queue "MyQueue" - these are all
passed directly to amq2 where they are delivered to the consumer - (as before, the producer-id
has changed).
>     - N.B. Immediately before the first message is received & forwarded by amq1,
amq1's log shows:
>         2013-09-11 12:05:56,639 | DEBUG | last stored sequence id set: -1 | org.apache.activemq.broker.ProducerBrokerExchange
| ActiveMQ Transport: tcp:///172.16.7.85:56880@61616
>       ---> This message only appears after fail-back, it doesn't appear earlier.
>            This is indicative of the network connection being treated differently after
fail-back.
> **********************
> ** Error occurs now **
> **********************
> ** Producer connects to amq3 & sends 20 messages on queue "MyQueue" (with a different
producer-ID)
>     - The first 10 are deleted by broker amq2 because it thinks that they have a duplicate
sequence ID.
>     - amq1 log shows:
>         2013-09-11 12:06:29,201 | DEBUG | suppressing duplicate message send [ID:bd7ewandymay-56895-1378897588954-0:1:1:1:1]
with producerSequenceId [1] less than last stored: 10 | org.apache.activemq.broker.ProducerBrokerExchange
| ActiveMQ Transport: tcp:///172.16.7.85:56880@61616
>         2013-09-11 12:06:29,223 | DEBUG | suppressing duplicate message send [ID:bd7ewandymay-56895-1378897588954-0:1:1:1:2]
with producerSequenceId [2] less than last stored: 10 | org.apache.activemq.broker.ProducerBrokerExchange
| ActiveMQ Transport: tcp:///172.16.7.85:56880@61616
>         ... snip ...
>         2013-09-11 12:06:29,396 | DEBUG | suppressing duplicate message send [ID:bd7ewandymay-56895-1378897588954-0:1:1:1:10]
with producerSequenceId [10] less than last stored: 10 | org.apache.activemq.broker.ProducerBrokerExchange
| ActiveMQ Transport: tcp:///172.16.7.85:56880@61616
>     - The last 10 are successfully forwarded to amq2, where they are consumed.
> ** Producer connects to amq3 & sends 30 messages on queue "MyQueue" (with a different
producer-ID)
>     - The first 20 are deleted by broker amq2 because it thinks that they have a duplicate
sequence ID.
>     - amq1 log shows:
>         2013-09-11 12:06:45,668 | DEBUG | suppressing duplicate message send [ID:bd7ewandymay-56899-1378897605440-0:1:1:1:1]
with producerSequenceId [1] less than last stored: 20 | org.apache.activemq.broker.ProducerBrokerExchange
| ActiveMQ Transport: tcp:///172.16.7.85:56880@61616
>         2013-09-11 12:06:45,682 | DEBUG | suppressing duplicate message send [ID:bd7ewandymay-56899-1378897605440-0:1:1:1:2]
with producerSequenceId [2] less than last stored: 20 | org.apache.activemq.broker.ProducerBrokerExchange
| ActiveMQ Transport: tcp:///172.16.7.85:56880@61616
>         ... snip ...
>         2013-09-11 12:06:45,959 | DEBUG | suppressing duplicate message send [ID:bd7ewandymay-56899-1378897605440-0:1:1:1:20]
with producerSequenceId [20] less than last stored: 20 | org.apache.activemq.broker.ProducerBrokerExchange
| ActiveMQ Transport: tcp:///172.16.7.85:56880@61616
>     - The last 10 are successfully forwarded to amq2, where they are consumed.
> It looks to me as if amq1 doesn't realise that the fail-back network connection established
by amq3 is a network connection & so isn't checking producer IDs.
> Details of why I'm trying this configuration:
> ---------------------------------------------
> Use case:
> ---------
> 1 central site.
> Multiple branches, each with a single branch server and multiple user PCs.
> Each branch only has 1 internet connection that is shared by branch server & PCs.
> Branch server is typically unreliable hardware & may go offline without notice.
> Resilience to network loss is important & so each PC & server has its own broker.
> Both branch server & PCs need to be able to communicate with the centre
> To reduce the number of connections into the centre, we would like a tree topology with
the branch server concentrating all branch PC messages & forwarding them to the centre.
> But, PCs generate a data feed that we want to be able to access at centre, even when
the branch server is offline.
> Proposed configuration:
> -----------------------
> Use a failover network connection on branch PCs & configure the connection to prioritise
a connection to the branch server, but open a direct connection to the centre if the branch
server is unavailable.

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