mturk 2004/04/14 23:32:33
Modified: jk/xdocs/jk2 configwebcom.xml
Log:
Update few missing docs. Thanks to Agnus Mezick.
Revision Changes Path
1.17 +109 -37 jakarta-tomcat-connectors/jk/xdocs/jk2/configwebcom.xml
Index: configwebcom.xml
===================================================================
RCS file: /home/cvs/jakarta-tomcat-connectors/jk/xdocs/jk2/configwebcom.xml,v
retrieving revision 1.16
retrieving revision 1.17
diff -u -r1.16 -r1.17
--- configwebcom.xml 13 Mar 2004 07:33:24 -0000 1.16
+++ configwebcom.xml 15 Apr 2004 06:32:33 -0000 1.17
@@ -156,26 +156,26 @@
<th>Default</th>
<th>Description</th>
</tr>
- <tr>
- <td>file</td>
- <td>No default value</td>
- <td>Name of the file that will be mmapped to use as shared
memory, If set to 'anonymous' use the anonymous shered memory</td>
- </tr>
- <tr>
- <td>size</td>
- <td>No default value</td>
- <td>Deprecated. Size of the file.</td>
- </tr>
- <tr>
- <td>slots</td>
- <td>256</td>
- <td>Number of shared memory slots. Set to the number of
child processes</td>
- </tr>
- <tr>
- <td>useMemory</td>
- <td>0</td>
- <td>Use process memory instead of shared memory. Useful for
single child mpm's</td>
- </tr>
+ <tr>
+ <td>file</td>
+ <td>No default value</td>
+ <td>Name of the file that will be mmapped to use as shared
memory, If set to 'anonymous' use the anonymous shered memory</td>
+ </tr>
+ <tr>
+ <td>size</td>
+ <td>No default value</td>
+ <td>Deprecated. Size of the file.</td>
+ </tr>
+ <tr>
+ <td>slots</td>
+ <td>256</td>
+ <td>Number of shared memory slots. Set to the number of
child processes</td>
+ </tr>
+ <tr>
+ <td>useMemory</td>
+ <td>0</td>
+ <td>Use process memory instead of shared memory. Useful for
single child mpm's</td>
+ </tr>
</table>
</p>
</section>
@@ -346,10 +346,18 @@
<tr>
<td>lb_factor</td>
<td>1</td>
- <td>
- Load balancing factor to use. At this moment, it'll be set on the worker,
- but in future it should be possible to use lb on a channel level.
- </td>
+ <td>Load balancing factor to use. The lower the
lb_factor the more often that tomcat will get requests but see
+ "level" below.</td>
+ </tr>
+ <tr>
+ <td>level</td>
+ <td>1</td>
+ <td>Worker Priority. Valid values are 0-3. The
functioning workers with the lowest level
+ will be checked for the lowest lb_value, and if
found will be run. The upper level workers are
+ only checked upon failure of all workers on ALL of
the levels below them. This is very
+ useful for implementing failover withing a cluster.
You could set the tomcat server local
+ on the same machine as the apache instance to level
0 and all of the other workers to level 1.
+ This would cause apache to only use the external
tomcats when the local tomcat is down.</td>
</tr>
<tr>
<td>group</td>
@@ -359,8 +367,13 @@
<tr>
<td>tomcatId</td>
<td>Automatically set to the localname ( host:port
)</td>
- <td>Must match the JVM route on tomcat Engine, for load
balancing</td>
+ <td>Must match the JVM route on tomcat the server.xml
Engine element, for load balancing</td>
</tr>
+ <tr>
+ <td>route</td>
+ <td>Automatically set to the localname ( host:port
)</td>
+ <td>Same as tomcatId</td>
+ </tr>
</table>
</p>
</subsection>
@@ -409,7 +422,8 @@
</p>
</subsection>
<subsection name="ajp13">
- <p>Default worker</p>
+ <p>Default worker. If a property is in both the worker and the
channel, you only need to define it in one place.
+ The channel passes down the properties to its worker. (at
least in the ajp13-channel.socket linkage)</p>
<p>
<table>
<tr>
@@ -427,28 +441,39 @@
</tr>
<tr>
<td>tomcatId</td>
- <td/>
- <td/>
+ <td>Automatically set to the localname ( host:port
)</td>
+ <td>Must match the JVM route on the tomcat server.xml
Engine element, for load balancing</td>
</tr>
<tr>
<td>route</td>
- <td/>
- <td/>
+ <td>Automatically set to the localname ( host:port
)</td>
+ <td>Same as tomcatId</td>
</tr>
<tr>
<td>group</td>
- <td/>
- <td/>
+ <td>lb</td>
+ <td>loadbalanced groups to which this channel and the
associated worker will be added, multivalued. You need to set it only if you have an
advanced setup with multiple clusters.</td>
+ </tr>
+ <tr>
+ <td>lb_factor</td>
+ <td>1</td>
+ <td>Load balancing factor to use. The lower the
lb_factor the more often that tomcat will get requests but see
+ "level" below.</td>
</tr>
<tr>
<td>level</td>
- <td/>
- <td/>
+ <td>1</td>
+ <td>Worker Priority. Valid values are 0-3. The
functioning workers with the lowest level
+ will be checked for the lowest lb_value, and if
found will be run. The upper level workers are
+ only checked upon failure of all workers on ALL of
the levels below them. This is very
+ useful for implementing failover withing a cluster.
You could set the tomcat server local
+ on the same machine as the apache instance to level
0 and all of the other workers to level 1.
+ This would cause apache to only use the external
tomcats when the local tomcat is down.</td>
</tr>
<tr>
<td>channel</td>
<td/>
- <td/>
+ <td>Communication channel used by the worker. Use the
full name of the channel (everything between the []'s).</td>
</tr>
<tr>
<td>max_connections</td>
@@ -574,7 +599,7 @@
<tr>
<td>level</td>
<td>INFO</td>
- <td>Log level. Supported: EMERG, ERROR, INFO, DEBUG</td>
+ <td>Text of the log level. Strings supported: EMERG, ERROR,
INFO, DEBUG</td>
</tr>
</table>
</p>
@@ -603,5 +628,52 @@
<subsection name="logger.apache2">
<p>Logger used in Apache2 servers, it normally in ends in error.log
</p>
</subsection>
+ </section>
+ <section name="How Load Balancing Works">
+ <p>The lb_factor and level properties combine to deliver a flexible static
load balancing solution.
+ The level property is used to create up to four pools over workers in
descending priority and lb_factor
+ is used to weight the workers within a pool. The lower the level the
more likely the worker is to be used
+ and the lower the lb_factor the more likely the worker is to be used.
Here is how the algorithm is
+ currently implemented:</p>
+ <p>
+(Assume that every worker's lb_value is set to their lb_factor)<br/>
+<br/><source>
+if (loadbalancer has a route) and (stickysession=1){<br/>
+ worker= loadbanlancer.getWorkerForRoute(route)<br/>
+ if worker.hasRedirect<br/>
+ redirect=worker.redirect<br/>
+ else if !worker.hasError<br/>
+ return worker<br/>
+ }<br/>
+<br/>
+selectedWorker=null<br/>
+foreach lb_level {<br/>
+ foreach worker in the level {<br/>
+ if worker.isNotWorking<br/>
+ continue<br/>
+ if selectedWorker == null<br/>
+ selectedWorker = worker<br/>
+ continue<br/>
+ if worker.lb_value < selectedWorker.lb_value<br/>
+ selectedWorker = worker<br/>
+ continue<br/>
+ }<br/>
+ if selectedWorker !=null<br/>
+ break<br/>
+}<br/>
+<br/>
+Reenable workers in error state if the timeout has passed()<br/>
+<br/>
+if selectedWorker !=null {<br/>
+ selectedWorker.lb_value += selectedWorker.lb_factor<br/>
+ if selectedWorker.lb_value > 255 {<br/>
+ foreach worker in load_balancer.workers[selectedWorker.level]<br/>
+ worker.lb_value=worker.lb_factor<br/>
+ }<br/>
+ }<br/>
+ return selectedWorker<br/>
+}<br/></source>
+</p>
+
</section>
</document>
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