[jboss-dev-forums] [Design of Messaging on JBoss (Messaging/JBoss)] - Re: JBM 2.0 Strict ordering via ordering groups

[ataylor]

Ive written some tests to verify that the current GroupingRoundRobinDistributionPolicy will provide strict ordering. Apart from one slight problem it does. 
The problem is that the GroupingRoundRobinDistributionPolicy tries available consumers until it finds one it can use. If one is busy then it tries the next available. If a queue holds a set of messages that belong to two different groups, and the queue has 2 consumers, as soon as consumer 1 is started it will try to deliver the messages and both groups can be pinned to the first consumer before the second consumer can be started. Of course The user could make sure that the session is started before any messages are delivered to the queue, but since the session:start method is non blocking the first messages could still arrive before  all consumers are started. making the start method a blocking call would fix this tho.

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