CLIENT_ACKNOWLEDGE with JmsTemplate - implicit message acknowledge each read [SPR-13255]

[spring-projects-issues]

Lubos Krnac opened SPR-13255 and commented

I found this code in JmsTemplate.doReceive(Session session, MessageConsumer consumer):

         Message message = doReceive(consumer, timeout);
if (session.getTransacted()) {
     // Commit necessary - but avoid commit call within a JTA transaction.
     if (isSessionLocallyTransacted(session)) {
              // Transacted session created by this template -> commit.
              JmsUtils.commitIfNecessary(session);
     }
}
else if (isClientAcknowledge(session)) {
     // Manually acknowledge message, if any.
     if (message != null) {
              message.acknowledge();
     }
}

Why is message acknowledged straight after reception before returning to application code? That effectively means we can't use JmsTemplate with CLIENT_ACKNOWLEDGE for bulk processing of messages. Does it relates somehow to #17587?

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Issue Links:

• JMS message always acknowledged even with CLIENT_ACKNOWLEDGE [SPR-12995] #17587 JMS message always acknowledged even with CLIENT_ACKNOWLEDGE

[spring-projects-issues]

Juergen Hoeller commented

Since we recently fine-tuned our documentation on JMS acknowledge modes (#17869), this should hopefully be clearer now: Not just in listener containers but also in JmsTemplate, CLIENT_ACKNOWLEDGE is just a mode of processing each message, essentially as an alternative to transactional acknowledgment.

Since we don't hold on to the same JMS Session there but rather re-acquire one for each message, manual acknowledgment in application code is not feasible here. For custom acknowledgment of a series of messages, you'd need to avoid JmsTemplate and perform direct invocations on an explicitly acquired JMS Session there, manually releasing it at the very end.

Juergen