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From "Charles Anthony" <>
Subject Memory Use
Date Fri, 17 Nov 2006 08:48:29 GMT

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"

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.



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