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From build...@apache.org
Subject svn commit: r856522 - in /websites/production/activemq/content: cache/main.pageCache how-can-i-support-priority-queues.html
Date Fri, 29 Mar 2013 18:23:07 GMT
Author: buildbot
Date: Fri Mar 29 18:23:06 2013
New Revision: 856522

Log:
Production update by buildbot for activemq

Modified:
    websites/production/activemq/content/cache/main.pageCache
    websites/production/activemq/content/how-can-i-support-priority-queues.html

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

Modified: websites/production/activemq/content/how-can-i-support-priority-queues.html
==============================================================================
--- websites/production/activemq/content/how-can-i-support-priority-queues.html (original)
+++ websites/production/activemq/content/how-can-i-support-priority-queues.html Fri Mar 29
18:23:06 2013
@@ -89,7 +89,19 @@
 </pre>
 </div></div>
 
-<p>The full range of priority values (0-9) are supported by the <a shape="rect"
href="jdbc-support.html" title="JDBC Support">JDBC</a> message store. For <a shape="rect"
href="kahadb.html" title="KahaDB">KahaDB</a> three priority levels are supported,
Low (&lt;5), Default (=5) and High (&gt;5).</p>
+<p>The full range of priority values (0-9) are supported by the <a shape="rect"
href="jdbc-support.html" title="JDBC Support">JDBC</a> message store. For <a shape="rect"
href="kahadb.html" title="KahaDB">KahaDB</a> three priority categories are supported,
Low (&lt; 4), Default (= 4) and High (&gt; 4).</p>
+
+<p>Since the message cursors (and client side) implement strict ordering of priorities,
it's possible to observe strict priority ordering if message dispatching can happen from the
cache and not have to hit the disk (i.e., your consumers are fast enough to keep up with producers),
or if you're using non-persistent messages that never have to flush to disk (which happens
by default using the FilePendingMessageCursor). However, once you hit a situation where consumers
are slow, or producers are just significantly faster, you'll observe that the cache will fill
up (possibly with lower priority messages) while higher priority messages get stuck on disk
and not available until they're paged in. In this case, you can make a decision to tradeoff
optimized message dispatching for priority enforcement. You can disable the cache, message
expiration check, and lower you consumer prefetch to 1 to ensure getting the high priority
messages from the store ahead of lower priority messages:<
 /p>
+
+<div class="code panel" style="border-width: 1px;"><div class="codeContent panelContent">
+<pre class="code-java">
+ &lt;destinationPolicy&gt;
+   &lt;policyMap&gt;
+     &lt;policyEntries&gt;
+       &lt;policyEntry queue=<span class="code-quote">"&gt;"</span> prioritizedMessages=<span
class="code-quote">"<span class="code-keyword">true</span>"</span> useCache=<span
class="code-quote">"<span class="code-keyword">false</span>"</span> expireMessagesPeriod=<span
class="code-quote">"0"</span> queuePrefetch=<span class="code-quote">"1"</span>
/&gt;
+    ...
+</pre>
+</div></div>
 
 <h3><a shape="rect" name="HowcanIsupportpriorityqueues-Alternativestrategies"></a>Alternative
strategies</h3>
 <h4><a shape="rect" name="HowcanIsupportpriorityqueues-UseSelectors"></a>Use
Selectors</h4>
@@ -118,7 +130,6 @@ JMSPriority &gt;= 4
 
 <p>To do this use the <a shape="rect" class="external-link" href="http://activemq.apache.org/camel/resequencer.html">Resequencer</a>
from the <a shape="rect" href="enterprise-integration-patterns.html" title="Enterprise
Integration Patterns">Enterprise Integration Patterns</a></p>
 
-
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