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From "James Strachan" <james.strac...@gmail.com>
Subject Re: 4.0 Consumer OutOfMemoryError bug?
Date Mon, 12 Jun 2006 08:18:37 GMT
For high performance we have an optimised acknowledgement mode which
is an attempt at acknowledging in batches rather than on every single
message. This is on by default in 4.0 but we've since disabled it as
some folks have experienced problems in some scenarios. Batching
acknowledgements causes the client to keep consumed messages around
until they are acknowledged; which further increases the RAM usage.
Given you are consumed over heap size you might want to disable this
feature...

http://incubator.apache.org/activemq/connection-configuration-uri.html

so connect via http://localhost:61616?jms.optimizeAcknowledge=false

(in 4.0.1 this will be the default value).

Other than that as I said, if you don't want a heap of such a large
size then just reduce down the prefetech; things won't run quite as
fast but if you've such little RAM on the boxes you are running
ActiveMQ then you have to trade off RAM with performance.



On 6/12/06, skarthik <karthik.sethuraman@necam.com> wrote:
>
> James,
>
> Thanks for your valuable time on following up on this issue.
>
> Well, I tried out some more test scenarios over the weekend and now DON'T
> think it is a memory leak problem, but definitely some kind of cleanup
> problem. Also I would like to reiterate that these issuses did not exist in
> RC2 build.
>
> I ran the test programs submitted in JIRA, with following parameters.
>
> Producer publishes messages of 10K size.
>
> The consumer heap was increased to 220 MB, to allow the consumer to store
> more than 20,000 messages (if required). Used the default topic prefetch
> values. (i think you mentioned it was 4000).
> With this heap size, the consumer runs out of memory after consuming around
> 19,000 messages.
>
> Now increased the consumer heap size to 225MB. Then a peculiar thing
> happens. After using up almost all of the heap memory (225 MB, and consuming
> about 21500-odd messages), the whole heap (about 210MB) is freed up in one
> shot. And this cycle (of using upto 225 MB and then freeing up all of it)
> continues after consuming every 21500-odd messages and the consumer never
> runs out of memory.
>
> So the question is why does it wait for upto 225 MB of memory to be used up
> before some kind of cleanup kicks in.
>
>  BTW, since the memory profile test case reported by Feng (my co-worker) in
> the JIRA issue-tracker, involved messages of 64K and a heap size of only
> 64MB, I can see why it might be difficult to convince that a problem exists.
> But I don't think the prefetch size is an issue, since the consumer consumes
> the messages at the same rate as the producer, unless the messages are kept
> around even after the consumer has processed it (my understanding of
> activemq internals/behavior is not deep). Also for our application (not the
> test code), we would like to keep the default prefetch size (around
> 4000-5000).
>
> Anyways, hope you guys get a chance to look at this problem as time is
> running out for us (we have a deadline to deilver by this month-end). Also
> would like to mention that the reason we are stressing on this issue is,
> that using activemq 4.0, our actual application (not the test code
> submitted) does not pass through our QA department. RC2 build does, but it
> has some known issues.
>
> Thanks,
> Karthik
>
> --
> View this message in context: http://www.nabble.com/4.0-Consumer-OutOfMemoryError-bug--t1707655.html#a4822824
> Sent from the ActiveMQ - User forum at Nabble.com.
>
>


-- 

James
-------
http://radio.weblogs.com/0112098/

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