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From rbolen <>
Subject Message Groups and long running transactions
Date Thu, 05 May 2011 19:59:51 GMT
We are looking at using message groups (activeMQ V5.5.0).  We are using an
external broker also.  We have a use case where a consumer could be
processing a long running transaction (multiple hours).  

My understanding of message groups is that a group is initially assigned to
a specific consumer and then stays on that consumer until a message comes
through with a -1 group sequence.  But in the case where a consumer is
processing a long transaction for group A and the consumer also has group B
assigned, messages for group B will have to wait for the long running group
A message to complete.  We'd like to avoid this. 

Is it true that even if we send a group B message with sequence -1, it would
only be processed after the long running transaction is complete anyway,
thus defeating the purpose of the -1 sequence?  Or does the broker process
it while the work on the client is being done thus freeing Group B to run on
another consumer.  (We're using prefetch of 1 but we could set it to 0 if it
would help.)

Is there a recommended way to avoid this situation?  Detect the large
payload and pre-emptively send -1 messages?  Create a new consumer
dynamically for large loads?


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