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From Guerrero <>
Subject Topic consumers are lost in a cyclic network
Date Mon, 19 Nov 2012 21:28:42 GMT
I am using activemq-core-5.7.0.

We are using broker-to-broker communications with conduit subscriptions to
reduce redundant messaging. We have a top-tier coordinating server, call it
broker A. We have two routing servers that each connect to A, call them
broker B and broker C.  We have remote applications that connect to both B
and C for redundancy, and client applications that connect to only one of B
or C. We only use topic messages for all communications between nodes.
Normally, all is well. However, we noticed some problems in the remaining
network when nodes were lost.  We were able to find steps to recreate the
problem as follows. Start the nodes in the order A, B, C, Remote, Client1,
Client2.  Stop node C.  At this point, some of the consumers from the Remote
were lost from Client1, while others remained. If we send a message from
Client1 on one of the topics that was lost, it doesn't leave the local

Tracing into the source of the network bridge, I suspected that
ConduitBridge.checkPaths was preventing one of the consumer paths from being
added to the list. I've attached a unit test,
, that uses JUnit, EasyMock, and activemq, that shows how messages may stop
forwarding depending on the order the consumers are added and removed from
the network bridge.  

When I comment out the check for checkPaths, my test and our application
seem to work.  However, ThreeBrokerQueueNetworkTest.testDuplicateQueueSubs
fails. I traced back the addition of checkPaths as a fix for  AMQ-2327
<>  , but cannot understand
why duplicate paths would be suppressed like this, when there is a flag to
suppress duplicate subscriptions for topics and queues and this is checked

Can anyone add any insights into why checkPaths exists, or what could be
wrong with the attached test case for addAndRemoveSameOrder()?

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