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From Gary Tully <gary.tu...@gmail.com>
Subject Re: Help understanding memory usage/limits
Date Wed, 07 Apr 2010 11:41:22 GMT
70% is the magic number, there is a cursorHighWaterMark destination policy
that defaults to 70% of system usage. your config can go to 80%

On 7 April 2010 12:15, Richard Holt <richard_holt@btopenworld.com> wrote:

>
> Hi Gary,
>
> It appears i am really not understanding this so could you clarify?
>
> You wrote:
>
> "Which ever destination tips it over the limit will have its memory usage
> flushed to disk because it is
> configured with a fileQueueCursor."
>
> and then wrote:
>
> "The salient point being that paging to disk is dependent on systemUsage
> configuration, not individual/per destination memory usage."
>
> To me, this says that once the combined destinations usage exceeds the
> systemusage/memoryusage of 20mb then the destination which did this is
> flushed.
>
> However, given that i have 16 * 1mb queues how can this ever occur? Surely
> this means my maximum memory is 16mb?
>
> So, flushing must be occuring when destinatons exceed the 1mb value
> irrespective of the systemusage/memoryusage setting...
>
> Or does it?
>
>
>
> Gary Tully wrote:
> >
> > richard, you have configured a 1mb limit for every queue because you use
> > the
> > ">". So the broker will keep up to 1mb of space in memory for each queue,
> > up
> > to 16MB for 16 queues.
> >
> > The paging (via fileQueueCursor) kicks in for each destination only when
> > 70%
> > of the shared system limit (20mb) is reached. Which ever destination tips
> > it
> > over the limit will have its memory usage flushed to disk because it is
> > configured with a fileQueueCursor. System usage will reduce by 1Mb and
> the
> > rest of the destinations will continue to use memory up to their limit.
> >
> > The salient point being that paging to disk is dependent on systemUsage
> > configuration, not individual/per destination memory usage.
> >
> >
> > On 7 April 2010 11:22, Richard Holt <richard_holt@btopenworld.com>
> wrote:
> >
> >>
> >> Sorry about the thread hijack - however if i have something like this
> >>
> >>        <destinationPolicy>
> >>            <policyMap>
> >>                <policyEntries>
> >>                    <policyEntry queue=">" memoryLimit="1mb"
> >> producerFlowControl="false">
> >>                        <pendingQueuePolicy>
> >>                            <fileQueueCursor/>
> >>                        </pendingQueuePolicy>
> >>                    </policyEntry>
> >>                </policyEntries>
> >>            </policyMap>
> >>        </destinationPolicy>
> >>
> >>                <systemUsage>
> >>                  <systemUsage>
> >>                        <memoryUsage>
> >>                          <memoryUsage limit="20mb"/>
> >>                        </memoryUsage>
> >>                        <storeUsage>
> >>                          <storeUsage limit="100mb"/>
> >>                        </storeUsage>
> >>                        <tempUsage>
> >>                          <tempUsage limit="100mb"/>
> >>                        </tempUsage>
> >>                  </systemUsage>
> >>                </systemUsage>
> >>
> >> and an Xmx of 32mb
> >>
> >> Once it reaches a limit of 1mb of messages per queue it will start to
> >> page
> >> out to disk.
> >>
> >> And the activemq system reserves 20mb of memory for itself?
> >>
> >> Is the 1mb then across all queues. So if i have 16 queues i in fact need
> >> 16mb. Because then the 20mb + 16 * 1mb will exceed my xmx value?
> >>
> >> Sorry if i am being obtuse but like the poster i am trying to see how
> the
> >> 3
> >> memory settings relate to each other.
> >>
> >> Coincidentally i have tested the above on 5.3.1 and it works really
> well.
> >> If
> >> i use 5.3 it breaks which i think is due to this
> >> https://issues.apache.org/activemq/browse/AMQ-2610 and this
> >>
> >> --
> >> View this message in context:
> >>
> http://old.nabble.com/Help-understanding-memory-usage-limits-tp28118112p28163080.html
> >> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
> >>
> >>
> >
> >
> > --
> > http://blog.garytully.com
> >
> > Open Source Integration
> > http://fusesource.com
> >
> >
>
> --
> View this message in context:
> http://old.nabble.com/Help-understanding-memory-usage-limits-tp28118112p28163528.html
> Sent from the ActiveMQ - User mailing list archive at Nabble.com.
>
>


-- 
http://blog.garytully.com

Open Source Integration
http://fusesource.com

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