ActiveMQ message group and load-balancing?

Question

in http://activemq.apache.org/message-groups.html, it is said that message groups provide load balancing of the processing of messages across multiple consumers.

Although I read the whole article, I have not understood the relation between message group and load-balancing. After all, there has been load-balance already before message group: message broker dispatch message according the speed of consumers' acknowledgment. So if there is load-balancing concerned with message group, it is a bigger one in term of granularity.

correct?

Any comments or insights are appreciated.

Answer 1

Well, it's not that complicated and might be somewhat confusing in the documentation.

Load balancing, as you say, is built in, since the broker dispaches messages among the available consumers. Message groups must often represents a unit that needs to be processed by a single node (or thread), perhaps even in order due to application logic.

If there are multiple message groups sent to a queue, they will be load balanced over multiple consumers.