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https://issues.apache.org/jira/browse/UIMA-1658?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12965276#action_12965276
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Jerry Cwiklik commented on UIMA-1658:
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Jorn, I actually found a work around for the failover problem. The problem you
are experiencing is in fact caused by AMQ bug. The bug is related to prefetch=0
and failover. As described here:
http://activemq.2283324.n4.nabble.com/jira-Created-AMQ-2877-Failover-and-prefetch-0-can-result-in-hung-consumers-if-the-MessagePull-commant-td2376741.html
such a scenario leads to a consumer hang as you've been noticing.
UIMA AS service by default uses a prefetch=0 for the service input queue. This
is done on purpose to enable fair load balancing at a slight cost of
throughput. Prefetch=0 means that the broker will not push messages to the
Consumer, and instead the Consumer pulls a single message from the broker
whenever it is ready. Such behavior facilitates fair load balancing among
available service instances. It also reduces memory footprint of UIMA AS
service as there are no outstanding messages in AMQ buffers to process.
Soooo, the work around is to simply change the prefetch value in the deployment
descriptor to 1 as shown below:
<inputQueue
brokerURL="failover:(tcp://x.y.z:portnumber1,tcp://x.y.z:portnumber2)?randomize=false"
endpoint="queue_name"
prefetch="1"/>
> UIMA AS worker does not respond to client initialize after failover
> -------------------------------------------------------------------
>
> Key: UIMA-1658
> URL: https://issues.apache.org/jira/browse/UIMA-1658
> Project: UIMA
> Issue Type: Bug
> Components: Async Scaleout
> Affects Versions: 2.3AS
> Environment: Ubuntu 8.10 Server, Java 1.6 and ActiveMQ 5.3.0
> Reporter: Jörn Kottmann
>
> A Pure Master Slave Broker is used to increase availability of the broker.
> More information about it can be found in the activemq documentation:
> http://activemq.apache.org/pure-master-slave.html
> In a test we simulated Master failure through killing the process with kill
> -9.
> Here is the log output from the worker node:
> INFO FailoverTransport - Successfully connected to
> tcp://XXX1:61616
> Here I stopped the master broker process with kill -9
> WARN FailoverTransport - Transport failed to tcp://XXX1:61616 ,
> attempting to automatically reconnect due to: java.io.EOFException
> WARN FailoverTransport - Transport failed to tcp://XXX1:61616 ,
> attempting to automatically reconnect due to: java.io.EOFException
> WARN FailoverTransport - Transport failed to tcp://XXX1:61616 ,
> attempting to automatically reconnect due to: java.io.EOFException
> INFO FailoverTransport - Successfully reconnected to
> tcp://XXX2:61616
> INFO FailoverTransport - Successfully reconnected to
> tcp://XXX2:61616
> INFO FailoverTransport - Successfully reconnected to
> tcp://XXX2:61616
> Afterwards the client was restarted but got a time out error during
> initialize.
> During initializes it sends a message to the worker nodes input queue, but
> this
> message if never retrieved.
> I used the activemq web interface to get some information about the message:
> Command 2001
> MessageFrom ID:XXXX-51032-1257865414664-0:1:1
> ServerURI failover:(tcp://XXX1:61616,tcp://XXX2:61616)?randomize=false
> MessageType 3000
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