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From "Maarten Dirkse" <Maarten.Dir...@filterworks.com>
Subject Broker hitting max memory with large persistent queue
Date Fri, 02 May 2008 07:01:56 GMT
Hi,
I've spent quite a bit of time trying to find a solution to this problem, but nothing that
I've come across in the documentation or the mailing list seems to help, so here goes:

I've got ActiveMQ set up to provide messaging between a chain of four components, connected
by three queues like so:
Component 1 --> queue A --> component 2 --> queue B --> component 3 --> queue
C --> component 4

Component 1 gets things going by messages and putting them on queue A. Component 2 then processes
these, and, for every message received, puts a message on queue B. Component three then does
the same thing as 2, generating an equal amount of message for component 4. Beside the queue
pipeline, components also communicate with each other using a "command" topic which produces
2 messages for every queue message that goes through the pipeline.
All queues are (pure JDBC) persistent, topics are non-persistent.

This setup works very well for low volumes of messages. At a certain point though, the first
component has to start producing messages at rates of several thousand per minute. Component
2 can't consume the messages at the rate they're produced, so the size of queue A slowly grows
into the thousands.

The problem is that, once the size of queue A gets large enough, the broker runs out of memory
and everything will screech to a halt (ie messages will be processed at a rate of 1 per minute
or something). At around 256mb of broker memory for example, it reaches 100% usage when queue
A contains around 16.000 messages. The number of messages that queue A can contain before
activemq becomes unusably slow grows and shrinks according to the amount of memory the broker
has.

What I don't get is why the broker slowly uses up all its memory for a queue that persists
its messages to the database (this actually happens, the database does fill up). I've read
a number of times in the documentation and mailing list that AMQ is capable of dealing with
queues that contain millions of messages, but in my setup it grinds to a halt at a number
far below that.

Can anyone tell me what I'm doing wrong?

Below is the setup used for the broker. Queues are defined in Spring using <amq:queue>
and producers and consumers use the Spring JMS template and JMS Listeners respectively. I'm
using AMQ 5.1 with Postgresql for persistence and Spring 2.5.3 to configure everything.

Broker config:
<broker id="broker" useJmx="true" brokerName="${brokerA.name}" xmlns="http://activemq.apache.org/schema/core"
dataDirectory="${activemq.data}">

  <persistenceAdapter>
    <jdbcPersistenceAdapter dataDirectory="${activemq.data}/jdbc" dataSource="#postgres-ds"
createTablesOnStartup="true" />
  </persistenceAdapter>

  <systemUsage>
    <systemUsage>
      <memoryUsage>
        <memoryUsage limit="128mb" />
      </memoryUsage>
    </systemUsage>
  </systemUsage>

  <transportConnectors>
    <transportConnector uri="tcp://localhost:61616" />
  </transportConnectors>
</broker>

Template and queue/topic config:

<beans>
  <amq:connectionFactory brokerURL="${broker.jmsUrl}" id="jmsFactory" dispatchAsync="true"
/>

  <bean id="scf" class="org.springframework.jms.connection.SingleConnectionFactory" p:targetConnectionFactory-ref="jmsFactory"
/>

  <bean class="org.springframework.jms.core.JmsTemplate" id="jmsTemplate" p:receiveTimeout="${jms.receivetimeout}"
p:connectionFactory-ref="scf" />

  <bean class="org.springframework.jms.core.JmsTemplate" id="commandTemplate" p:receiveTimeout="${jms.receivetimeout}"
p:explicitQosEnabled="true"
    p:priority="4" p:deliveryMode="2" p:timeToLive="120000" p:connectionFactory-ref="scf"
p:defaultDestination-ref="commandTopic" />

  <amq:queue id="A" physicalName="queue.A" />
  <amq:queue id="B" physicalName="queue.B" />
  <amq:queue id="C" physicalName="queue.C" />

  <amq:topic id="commandTopic" physicalName="command.topic" />
</beans>

Thanks in advance,
Maarten



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