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<h1>JMS Message Producer Rate Limiting</h1>
<p>With ActiveMQ you can specify a maximum send rate at which a JMS MessageProducer will send messages.
This can be specified when creating or deploying the connection factory. See <code>activemq-jms.xml</code></p>
<p>If this value is specified then ActiveMQ will ensure that messages are never produced at a rate higher than
specified. This is a form of producer <i>throttling</i>.</p>
<h2>Example step-by-step</h2>
<p>In this example we specify a <code>producer-max-rate</code> of <code>50</code> messages per second in the <code>activemq-jms.xml</code>
file when deploying the connection factory:</p>
<pre class="prettyprint">
<code>
<connection-factory name="ConnectionFactory">
<connector-ref connector-name="netty-connector"/>
<entries>
<entry name="ConnectionFactory"/>
</entries>
<!-- We limit producers created on this connection factory to produce messages at a maximum rate
of 50 messages per sec -->
<producer-max-rate>50</producer-max-rate>
</connection-factory>
</code>
</pre>
<p>We then simply send as many messages as we can in 10 seconds and note how many messages are actually sent.</p>
<p>We note that the number of messages sent per second never exceeds the specified value of <code>50</code> messages per second.</p>
<p><i>To run the example, simply type <code>mvn verify</code> from this directory</i></p>
<ol>
<li>Create an initial context to perform the JNDI lookup.</li>
<pre class="prettyprint">
<code>initialContext = getContext(0);</code>
</pre>
<li>Perfom a lookup on the queue</li>
<pre class="prettyprint">
<code>Queue queue = (Queue)initialContext.lookup("/queue/exampleQueue");</code>
</pre>
<li>Perform a lookup on the Connection Factory</li>
<pre class="prettyprint">
<code>ConnectionFactory cf = (ConnectionFactory)initialContext.lookup("/ConnectionFactory");</code>
</pre>
<li>Create a JMS Connection</li>
<pre class="prettyprint">
<code>connection = cf.createConnection();</code>
</pre>
<li>Create a JMS Session</li>
<pre class="prettyprint">
<code>Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);</code>
</pre>
<li>Create a JMS Message Producer</li>
<pre class="prettyprint">
<code>MessageProducer producer = session.createProducer(queue);</code>
</pre>
<li>Send as many messages as we can in 10 seconds</li>
<pre class="prettyprint">
<code>
final long duration = 10000;
int i = 0;
long start = System.currentTimeMillis();
while (System.currentTimeMillis() - start <= duration)
{
TextMessage message = session.createTextMessage("This is text message: " + i++);
producer.send(message);
}
long end = System.currentTimeMillis();
double rate = 1000 * (double)i / (end - start);
System.out.println("We sent " + i + " messages in " + (end - start) + " milliseconds");
System.out.println("Actual send rate was " + rate + " messages per second");
</code>
</pre>
<li>We note that the sending rate doesn't exceed 50 messages per second. Here's some example output from a real
run</li>
<pre class="prettyprint">
<code>
[java] Will now send as many messages as we can in 10 seconds...
[java] We sent 500 messages in 10072 milliseconds
[java] Actual send rate was 49.64257347100874 messages per second
</code>
</pre>
<li>For good measure we consumer the messages we produced.</li>
<pre class="prettyprint">
<code>
MessageConsumer messageConsumer = session.createConsumer(queue);
connection.start();
System.out.println("Now consuming the messages...");
i = 0;
while (true)
{
TextMessage messageReceived = (TextMessage)messageConsumer.receive(5000);
if (messageReceived == null)
{
break;
}
i++;
}
System.out.println("Received " + i + " messages");
</code>
</pre>
<li>Be sure to close our resources!</li>
<pre class="prettyprint">
<code>
finally
{
if (initialContext != null)
{
initialContext.close();
}
if (connection != null)
{
connection.close();
}
}</code>
</pre>
</ol>
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