[jboss-cvs] JBoss Messaging SVN: r3864 - branches/Branch_Stable/docs/userguide/en/modules.

[jboss-cvs-commits at lists.jboss.org]

Author: timfox
Date: 2008-03-11 09:08:26 -0400 (Tue, 11 Mar 2008)
New Revision: 3864

Modified:
   branches/Branch_Stable/docs/userguide/en/modules/configuration.xml
Log:
Clarification to docs about prefetchSize


Modified: branches/Branch_Stable/docs/userguide/en/modules/configuration.xml
===================================================================
--- branches/Branch_Stable/docs/userguide/en/modules/configuration.xml	2008-03-11 02:51:23 UTC (rev 3863)
+++ branches/Branch_Stable/docs/userguide/en/modules/configuration.xml	2008-03-11 13:08:26 UTC (rev 3864)
@@ -2156,13 +2156,9 @@
       <section id="conf.connectionfactory.attributes.prefetchsize">
         <title>PrefetchSize</title>
 
-        <para>Each client side consumer maintains a local buffer of messages
-        from which it consumes. The server typically sends messages as fast as
-        it can to the consumer, and when the consumer is full it sends the
-        server a "stop" message to say it is full. When it clears enough space
-        it sends a "start" message to ask the server to continue sending
-        messages. The prefetchSize determines the size of this buffer. Larger
-        values give better throughput.</para>
+        <para>This parameter specifies the window size in numbers of messages, for consumer flow control.
+	The window size determines the number of messages a server can send to a consumer without blocking.
+        Each consumer maintains a buffer of messages from which it consumes. Please note that TCP also implements its own flow control, so if you set this to too large a number, then the TCP window size may be hit before the prefetchSize, which can cause writes to block.</para>
       </section>
 
       <section id="conf.connectionfactory.attributes.slowconsumers">
@@ -2170,7 +2166,7 @@
 
         <para>If you have very slow consumers, then you probably want to make
         sure they don't buffer any messages. Since this can prevent them from
-        being consumed by faster consumers.</para>
+        being consumed by faster consumers. Setting this to true is equivalent to setting PrefetchSize to 1</para>
       </section>
 
       <section id="conf.connectionfactory.attributes.tckstrictbehavior">