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From peterchenadded <>
Subject Re: Broker Memory Usage is 100% and tries to flush to disk with Null Pointer Exception
Date Mon, 14 Apr 2014 02:05:32 GMT
Please note we are using the following:

ActiveMQ: 5.5.1
Jrockit: Oracle JRockit(R) (build
R28.2.4-14-151097-1.6.0_33-20120618-1634-linux-x86_64, compiled mode)

artnaseef wrote
> If I understand correctly, the issue is reaching 100% memory usage.  Are
> the attempts to increase memory usage by spamming the broker intended to
> reproduce the problem?

Yes that is correct, need to understand how the broker memory usage can be
increased sustained load. i.e. how is it counting the memory usage and are
there situations when the memory usage is count incorrectly?

artnaseef wrote
> To find where memory is being used, look at QueueSize, for Queues, and
> PendingQueueSize, for Topics, attributes of the Queue and Topic
> Subscription MBeans via JMX.  Queue sizes can also be seen via the
> webconsole. 
> Typically, 100% memory usage means slow consumption.  With that in mind, I
> recommend collecting metrics with a JMX tool, such as jmxtrans, and
> feeding into a solution that can be used to monitor and report, such as
> one using OpenTSDB and Zabbix.  Then monitor for slow consumption - either
> by setting limits to QueueSize and PendingQueueSize, or by monitoring
> AverageEnqueueTime. 

We will have a look at these attributes and provide the numbers.

artnaseef wrote
> As for the NullPointerException - can you provide a small test case that
> reproduces the problem?  Also, does it happen on the latest ActiveMQ
> builds? 

One test case would be when the broker memory usage has exceeded 70% of it's
maximum and it needs to flush to disk. However, we are not able to produce
messages in such a way that the broker memory usage increases.

artnaseef wrote
> It's unclear why the attempts to reproduce (assuming that's what they are)
> do not see memory usage increase.  One question - which memory usage value
> is being monitored?  The broker's (top-level) memory usage, or memory
> usage of a specific destination?

We are measuring the memory usage of the broker in JConsole. 

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