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From Richard Holt <richard_h...@btopenworld.com>
Subject Re: Help understanding memory usage/limits
Date Wed, 07 Apr 2010 11:15:41 GMT

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.


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