So I don't want to repeat a Thread Discussion ( http://activemq.2283324.n4.nabble.com/slow-consumer-not-working-td2346908.html <http://activemq.2283324.n4.nabble.com/slow-consumer-not-working-td2346908.html> ) but I am not sure the questions were answered about how to control "prefetch" on consumers using the API. And the Javadocs do not seem to provide any details on how to use the "prefetch" controls http://activemq.apache.org/maven/apidocs/index.html?org/apache/activemq/ActiveMQPrefetchPolicy.html <http://activemq.apache.org/maven/apidocs/index.html?org/apache/activemq/ActiveMQPrefetchPolicy.html> I do not believe the default behavior of ActiveMQ follows the "competing consumer" model as indicated http://activemq.apache.org/clustering.html.If I want to make use of an entire compute cluster (message consumers) most efficiently, I would want the fastest consumers to take up the slack if slower consumers are not able to keep up. The slow consumer can be cause by a variety of reasons but it could be nothing more than a mixture of hardware varying in speed. When I run a test-harness that introduces latency into 1 of 3 "competing" consumers and I send 99 messages from a producer at an even rate, I see that each of the 3 consumers ingests 33 messages. The 1 that is sleeping between message handling continues to chug away at its load and the others sit idle. Even when I stop a fast consumer and restart it, the slow one still chugs away on his even portion of the total. If I run the same test-harness with IBM MQ and the same JMS producer / consumer code. I see the slow consumer take what he can and the balance of the load be evenly distributed across the fast consumers - as I would expect.I cannot see any use where the default ActiveMQ behavior is desirable. Regardless, it does seem to be controlled by a "prefetch" limit. It seems like one could control the default for all use cases with the setAll() ?void setAll(int i) void setDurableTopicPrefetch(int durableTopicPrefetch) void setMaximumPendingMessageLimit(int maximumPendingMessageLimit)Sets how many messages a broker will keep around, above the prefetch limit, for non-durable topics before starting to discard older messages.void setOptimizeDurableTopicPrefetch(int optimizeAcknowledgePrefetch) void setQueueBrowserPrefetch(int queueBrowserPrefetch) void setQueuePrefetch(int queuePrefetch) void setTopicPrefetch(int topicPrefetch) So any guidance on using the ActiveMQPrefetchPolicy class in general is appreciated - as well while I am assuming I can set the default to allow competing customers to work at their combined optimal compute capacity and there is a setting for that... Are there any pitfalls as well?Thank you
-- View this message in context: http://activemq.2283324.n4.nabble.com/Default-pre-fetch-behavior-of-ActiveMQ-and-the-competing-consumer-tp4712108.html Sent from the ActiveMQ - User mailing list archive at Nabble.com.
