Hi, I have a problem where TemporaryQueues are left (with 0 consumers) after the applications creating them have finished.
This scenario occurs for both ActiveMQ 4.1.1 and 5.3.0 on my P4 2.6 GHz, 3 GB RAM, Ubuntu 9.10, Sun JDK, default settings for ActiveMQ. I've tried to recreate a simpler version of the scenario. Basically I have a server that creates a Topic where clients that wants to subscribe may post a message (with a TemporaryQueue as the JMS reply) in order to be added. The server then has a thread that sends messages to all the TemporaryQueues. (I know a simple Topic could push the updates here, but in the real system the clients can receive information only intended for one single client.) In my scenario the server is faster at generating messages than the clients are in processing them so the queues start to build up. Pretty soon (if clients are added and removed once a minute or so) it will hit a limit and the processing of messages in the broker seems to come to a halt. I think it is when the prefetch limit is reached. The real problem here is that if a client disconnects successfully (might hang in the broker communication) it is possible for the server to "resurrect" its TemporaryQueue, probably by sending prefetchbuffered messages to it. This way the TemporaryQueue is left on the broker with no consumer (the client disconnected) with its queued up messages counting towards the prefetch limit. By running JConsole and purging the queue I can get the broker to wake up, but if many messages are queued up the consumerless TempQueue will queue those messages which might again cause the prefetch limit to be reached and halt the broker. Also, I've seen old TemporaryQueues that were removed minutes ago come back and start queueing buffered messages when I start purging other consumerless TempQueues. In short I think there are two problems here. First, the detection of the client disconnection is not instant on the server. This makes it possible to send messages to the TemporaryQueue without getting an exception after it should have been removed. The second is that the TemporaryQueue is able to resurrect after its creator/consumer has left. In other words it has outlived its connection. I attach a simple client and server that are able to reproduce this reliably (at least on my computer). Just run the server and maybe two clients. Restart the clients perhaps 1-2 times per minute and the issue will show pretty quickly. At least on my P4, maybe a computer with multiple cores will behave different. Regards Zemus http://old.nabble.com/file/p27130529/TestClient.java TestClient.java http://old.nabble.com/file/p27130529/ClientShutdownHook.java ClientShutdownHook.java http://old.nabble.com/file/p27130529/TestServer.java TestServer.java http://old.nabble.com/file/p27130529/ServerShutdownHook.java ServerShutdownHook.java -- View this message in context: http://old.nabble.com/Problems-with-prefetch-and-TemporaryQueues-tp27130529p27130529.html Sent from the ActiveMQ - User mailing list archive at Nabble.com.
