If there was a large number of bytes/messages out for delivery to consumers, and consumers are waiting for a complete batch of messages before sending an ack, there is a risk of resource starvation in the broker; the broker will not page in more messages while waiting for an ack and the consumers are waiting for messages before sending an ack.

This is a change in behavior in AMQ 7.11 with the removal of page caching, and should be documented clearly.

To mitigate, either increase the number of bytes the broker is allowed to read from paging:

<max-read-page-bytes>100M</max-read-page-bytes>

Or modify clients to reduce batch size.