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https://issues.apache.org/jira/browse/AMQ-2629?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13089398#comment-13089398
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Sree Panchajanyam D commented on AMQ-2629:
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Non-persistent messages are stored in memory before they are sent to consumers.
CursoryMemoryUsage indicates the memory(heap) used by non-persistent messages.
This is usually capped at 70% of heap space. This is configuration is made in
activemq.xml. When the cursory memory usage goes beyond the capped value( say
70% by default) the incoming messages are written to tempstore( a location on
disk) and all the messages from memory are flushed to tempstore, here the
CursorMemoryUsage becomes 0%. When you hit tempstore the dequeueing and
enqueueing slows down because of disk writes.
When queue size increases CursorMemoryUsage increases till a capped value and
then becomes zero . After this enqueue and dequeue operations slow down due to
disk writes involved.
> What the relationship is among "CursorMemoryUsage" and "QueueSize"
> ------------------------------------------------------------------
>
> Key: AMQ-2629
> URL: https://issues.apache.org/jira/browse/AMQ-2629
> Project: ActiveMQ
> Issue Type: Bug
> Components: Message Store
> Affects Versions: 5.2.0
> Environment: Windows2003 server - JDK 1.5.0_09-b03
> Reporter: SPES G200
> Fix For: 5.2.0
>
>
> Hi to everybody,
>
> In my application, that has 2 fast producers and 1 slow consumer, after some
> hours of job, where "Queue Size" various among 0 and 1000,
> "CursorMemoryUsage" it begins to increase him. This phenomenon provokes a
> deceleration both of "Enqueue" that "Dequeue", and even if they are stopped
> the producers the speed of "dequeue" it doesn't increase. When "Queue Size"
> returns to 0, "CursorMemoryUsage" it doesn't decrease.
>
> When this phenomenon happens I have seen that also her "Heap Memory Usage" it
> grows.
>
> Do you have some explanation to this phenomenon?
> What the relationship is among "CursorMemoryUsage" and "QueueSize."
>
> Thanks in advance
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