Enabling message paging in WebLogic JMS queues

By default, the messages in WebLogic JMS queues are kept in memory (in the Java™ heap). You should consider protecting them against situations where a large number of messages could cause the JMS server to fail because it has run out of space in its Java heap.

This could happen if there are a significantly large number of messages in the queue or exceptionally large message bodies. In those situations, the JVM could run out of space in its heap.

The best way to find out how much JVM heap you need is to create a large number of messages in your test queues and see how much memory is used. The amount of heap required differs for each implementation.

To protect against situations where the WebLogic JMS heap fills up, you could enable byte or message paging. When the number of bytes or messages exceeds specified thresholds, WebLogic JMS server pages out the message body (but not the message header) to a paging file store. This approach can reduce the likelihood of a JVM crash. You can still run out of JMS Server heap if the queue has a lot of message headers.

As a draconian measure, you can set the maximum message parameter. When set, this parameter puts a hard limit on the number of messages that can be in the queue. When this threshold is reached, new messages are rejected with an error message. As a result, you have to ensure that message producers are architected to correctly handle message maximum exceptions – for example, the message producers may want to queue the messages and retry later.