DefaultMessageListenerContainer, maxConcurrentConsumers and shrinking of consumers

Hi,

I am using the DefaultMessageListenerContainer and it states in the documentation that is I use maxConcurrentConsumers then threads will shrink back to the concurrentConsumers value after a specific time. I don't see that happening, with the number of threads staying at the maxConcurrentConsumers value.

I use default values for all the rest. This means, based on my understanding, that maxMessagesPerTask remains at its Integer.MIN_VALUE, and the thread executor is the SimpleAsyncTaskExecutor.

Looking at the runnable code, it looks like this code will be executed:

while (isActive()) {
waitWhileNotRunning();
if (isActive()) {
messageReceived = invokeListener();
}
}

And it seems like it will never exit the thread in order to perform the dynamic shrinking (which based on the javadoc it should shrink).

Am I missing something?

I think it will only work when maxMessagesPerTask property is set no non negative value. Is so, instead of never ending loop you mentioned this code is invoked:

Code:

---

int messageCount = 0;
while (isRunning() && messageCount < maxMessagesPerTask) {
        messageReceived = (invokeListener() || messageReceived);
        messageCount++;
}

---

Here would be confirmation of my theory (though growing does work without maxMessagesPerTask) - fragment "Note: shrink/grow only works if the maxMessagePerTask property is set to a positive value, preferably 1.".

This would be actually strange that documentation says nothing about such requirement.

Is what I think correct?

But in this case, using the SimpleAsyncTaskExecutor, new thread will be created each time (pass the maxMessages marker), and the idle settings won't take affect?

Yes, and that is why I use thread pool