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From "Aaron Phillips (Created) (JIRA)" <j...@apache.org>
Subject [jira] [Created] (AMQ-3575) Failover transport race condition causes intermittent incomplete bridge connections
Date Wed, 02 Nov 2011 16:45:35 GMT
Failover transport race condition causes intermittent incomplete bridge connections
-----------------------------------------------------------------------------------

                 Key: AMQ-3575
                 URL: https://issues.apache.org/jira/browse/AMQ-3575
             Project: ActiveMQ
          Issue Type: Bug
          Components: Transport
    Affects Versions: 5.5.0
         Environment: CentOS 5.5 and Mac OSX10
            Reporter: Aaron Phillips
             Fix For: NEEDS_REVIEWED


There is a race condition in FailoverTransport.java that sometimes results in preventing network
bridge connections from starting.  This is a serious issue as it was preventing us from setting
up failover connections between brokers.  I would have asked it be critical if it weren't
for a workaround.  The workaround I have found is as follows:

Turn on activemq thread pooling option to avoid failover bridge connection race condition.
 Change the following property to in your start script to make it false like so.  Somehow
this got me around the problem of the wrong thread sometimes winning:
-Dorg.apache.activemq.UseDedicatedTaskRunner=false

I've attached a unit test to be dropped in activemq-core/src/test/java/org/apache/activemq/transport/failover.
 The unit test shows that when a delay is introduced in setting of the TransportListener,
the BrokerInfo command required to complete the bridge connection will never be processed.
 There are two unit tests in this class and both are designed to pass.  The test called "testTcpThreadWinsPreventsCompletionOfBridge"
passes by asserting that it *did not* receive the BrokerInfo command.  You can see through
setting the delay value that you can control whether the Main thread wins (in which case all
is well), or the TCP thread wins (in which case the network bridge is hung and fails to start)

Note, this issue only affects network bridge connections which are setup with failover transport,
such as a broker that connects to a Master-Slave pair, e.g. failover://(tcp://master:61616,tcp://slave:61616)?randomize=false

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