DefaultMessageListenerContainer, maxConcurrentConsumers and shrinking of consumers

[kimchy]

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?

[feat]

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:

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?

[kimchy]

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?

[feat]

Yes, and that is why I use thread pool