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Subject svn commit: r884984 - in /websites/production/activemq/content: cache/main.pageCache what-is-the-prefetch-limit-for.html
Date Thu, 31 Oct 2013 19:21:55 GMT
Author: buildbot
Date: Thu Oct 31 19:21:55 2013
New Revision: 884984

Production update by buildbot for activemq


Modified: websites/production/activemq/content/cache/main.pageCache
Binary files - no diff available.

Modified: websites/production/activemq/content/what-is-the-prefetch-limit-for.html
--- websites/production/activemq/content/what-is-the-prefetch-limit-for.html (original)
+++ websites/production/activemq/content/what-is-the-prefetch-limit-for.html Thu Oct 31 19:21:55
@@ -32,15 +32,6 @@
-          <link href=''
rel='stylesheet' type='text/css' /> 
-      <link href=''
rel='stylesheet' type='text/css' /> 
-      <script src='' type='text/javascript'></script>

-              <script src=''
-      <script type="text/javascript"> 
-        SyntaxHighlighter.defaults['toolbar'] = false; 
-        SyntaxHighlighter.all(); 
-      </script> 
     Apache ActiveMQ &#8482; -- What is the prefetch limit for
@@ -127,7 +118,7 @@ consumer = session.createConsumer(queue)
 <p>Consuming messages from a pool of consumers an be problematic due to prefetch. Unconsumed
prefetched messages are only released when a consumer is closed, but with a pooled consumer
the close is deferred (for reuse) till the consumer pool closes. This leaves prefetched messages
unconsumed till the consumer is reused. This feature can be desirable from a performance perspective
but it can lead to out-of-sequence messages when there is more than one consumer in the pool.<br
 For this reason, the <a shape="rect" class="external-link" href="">org.apache.activemq.pool.PooledConnectionFactory</a>
does <b>not</b> pool consumers. <br clear="none">
 The problem is visible with the Spring DMLC when the cache level is set to CACHE_CONSUMER
and there are multiple concurrent consumers.<br clear="none">
-One solution to this problem is to use a prefetch of 0 for a pooled consumer, in this way,
it will poll for messages on each call to <tt>receive(timeout)</tt>.</p>
+One solution to this problem is to use a prefetch of 0 for a pooled consumer, in this way,
it will poll for messages on each call to <tt>receive(timeout)</tt>.  Another
option is to enable the <a shape="rect" class="external-link" href="">AbortSlowAckConsumerStrategy</a>
on the broker to disconnect consumers that have not acknowledged a Message after some configurable
time period. </p>
 <h3><a shape="rect" name="Whatistheprefetchlimitfor-RamversusPerformancetradeoff"></a>Ram
versus Performance tradeoff</h3>

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