Hi, We're doing a stress test on our app, and we're trying to test with thousands of concurrent users.
Each user has a connection to a (standalone) broker, and each user (currently) has two temporary queues. There is also a central "normal" queue. We are getting garbage collection total freezes after a while with this config. We are just using a tcp: transport, and to begin with we were not using persistence. This is using activemq 4.0 (ish - a little before the release). We then enabled persistence (derby + journal) - and we lasted a little longer, but the same issue arose. I then wrote a little test harness that simply created 50 connections, with two temp queues per session - and the heap grew by 10 Mb (non gc-able). That works out at about 200k per connection; so, for 1000 connections, that's 200 Mb on the heap before we even send any messages ! Is there anyway to decrease this amount-per-connection ? Is there some kind of configureable buffer per connection somewhere ? Our application server IS processing messages as the stress test progresses, and JConsole is showing that the main queue rarely has more than 30 messages, and typically only has 5 or six sitting there. Is there any way to see how BIG these messages are ? I don't think they'll be very big (50-60k is my guess), but I'd like to know. I thought the introduction of the persistence would reduce the memory usage, but it seems not. I've just downloaded 4.0.2, and tried my how-much-space-per-connection test - and it remains at 200k ish. I'll give the stress test using 4.02 a try in a bit - but any pointers would be helpful; I've run Jprofiler against the broker, but nothing obvious is showing up. Cheers, Charles.
