svn commit: r903975 - in /websites/production/activemq/content: cache/main.pageCache pluggable-storage-lockers.html

[bu...@apache.org]

Author: buildbot
Date: Thu Mar 27 23:21:46 2014
New Revision: 903975

Log:
Production update by buildbot for activemq

Modified:
    websites/production/activemq/content/cache/main.pageCache
    websites/production/activemq/content/pluggable-storage-lockers.html

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

Modified: websites/production/activemq/content/pluggable-storage-lockers.html
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--- websites/production/activemq/content/pluggable-storage-lockers.html (original)
+++ websites/production/activemq/content/pluggable-storage-lockers.html Thu Mar 27 23:21:46 2014
@@ -106,7 +106,7 @@
 		</locker>
 	</jdbcPersistenceAdapter>
 &lt;/persistenceAdapter&gt;]]></script>
-</div></div><p>The lease based lock is acquired by blocking at startup. It is then retained for a period whose duration (in ms) is given by the <code>lockKeepAlivePeriod</code> attribute. To retain the lock the master broker periodically extends its lease by <code>lockAcquireSleepInterval</code> milliseconds each time. In theory, therefore, the master broker is always (<code>lockAcquireSleepInterval</code>&#160;<code>-</code> <code>lockKeepAlivePeriod</code>) ahead of the slave broker w.r.t the lease. It is imperative that <code>lockAcquireSleepInterval &gt; lockKeepAlivePeriod</code>, to ensure the lease is always current. As of ActiveMQ 5.9.0 a warning message is logged if this condition is not met.</p><p>In the simplest case, the clocks between master and slave must be in sync for this solution to work properly. If the clocks cannot be in sync, the locker can use the system time from the database CURRENT TIME and adjust the timeouts in accordance with their local variance from th
 e db system time. If&#160;<code>maxAllowableDiffFromDBTime</code> is greater than zero the local periods will be adjusted by any delta that exceeds <code>maxAllowableDiffFromDBTime</code>.</p>    <div class="aui-message hint shadowed information-macro">
+</div></div><p>In order for this mechanism to work correctly, each broker in the master/slave pair must have a different <code>brokerName</code> attribute defined on the <code>broker</code> tag, as it is this value that is used to reserve a lease.</p><p>The lease based lock is acquired by blocking at startup. It is then retained for a period whose duration (in ms) is given by the <code>lockKeepAlivePeriod</code> attribute. To retain the lock the master broker periodically extends its lease by <code>lockAcquireSleepInterval</code> milliseconds each time. In theory, therefore, the master broker is always (<code>lockAcquireSleepInterval</code>&#160;<code>-</code> <code>lockKeepAlivePeriod</code>) ahead of the slave broker with regard to the lease. It is imperative that <code>lockAcquireSleepInterval &gt; lockKeepAlivePeriod</code>, to ensure the lease is always current. As of ActiveMQ 5.9.0 a warning message is logged if this condition is not met.</p><p>In the simplest case, the clocks
  between master and slave must be in sync for this solution to work properly. If the clocks cannot be in sync, the locker can use the system time from the database CURRENT TIME and adjust the timeouts in accordance with their local variance from the db system time. If&#160;<code>maxAllowableDiffFromDBTime</code> is greater than zero the local periods will be adjusted by any delta that exceeds <code>maxAllowableDiffFromDBTime</code>.</p>    <div class="aui-message hint shadowed information-macro">
                             <span class="aui-icon icon-hint">Icon</span>
                 <div class="message-content">
                             <p>It is important to know if the default rules your JDBC driver uses for converting TIME values are JDBC compliant. If you're using MySQL, for example, the driver's JDBC URL should contain&#160;<code>useJDBCCompliantTimezoneShift=true</code> to ensure that TIME value conversion is JDBC compliant. If not the locker could report a large time difference when it compares the retrieved lease expiration time against the current system time. Consult your JDBC driver's manual for more details.</p>