IBM BS029ML Self Help Guide - Page 162

Web container, Servers, Application Servers, WebSphere_Portal, Additional Properties

Page 162 highlights

5.2.5 Web container The Web container serves to "gate" the amount of incoming HTTP requests. The larger the number of threads, the higher the number of concurrent requests are allowed to enter the Web container. At some point, however, the number of concurrent threads being processed by the Web container can overwhelm its abilities. Display Caching should be explicitly enabled for the Portal Web container. In addition, if the WebSphere Dynacache mechanism is going to be utilized by the Portal for Portlet fragment caching, the enablement of Servlet Caching is a prerequisite. To view or modify the Web container settings from the WebSphere Application Server Administrative Console, select Servers → Application Servers → WebSphere_Portal → Additional Properties → Thread Pools → Web Container. Table 5-5 shows the default and recommended settings. Table 5-5 Web container settings Parameter Enable Servlet Caching Default value Disabled Recommended value Enabled In terms of Portal performance, an increase in the maximum number of threads can offer an improvement. However, care should be taken, as increasing the value too high above the suggested optimum value of 75 threads can lead to greater %CPU and memory usage. Setting the number of minimum threads equal to the number of maximum threads does not normally offer any immediate improvement after startup. An examination of a Java thread dump will fail to show a thread count matching the minimum thread setting immediately after initialization. To view or modify the Web container settings from the WebSphere Application Server Administrative Console, select Servers → Application Servers → WebSphere_Portal → Additional Properties → Thread Pools → Web Container. Table 5-6 shows the default and recommended values. Table 5-6 Web container settings Parameter Minimum Threads Maximum Threads Is Growable Default value 10 50 Disabled Recommended value 55 75 Disabled Under no circumstances should the "Allow thread allocation beyond maximum thread size" feature be enabled. Permitting this setting can lead to runaway thread growth. The WebSphere queuing mechanism is designed to handle burst traffic, and occasional "floods" of the Web container should subsume relatively quickly in most circumstances. Attention: Our experience tells us that one commonly made mistake is that many customers increase the maximum thread pool setting beyond the recommended value in the hope of increasing performance. As this runs the risk of overwhelming the ability of a single JVM, our advice instead is to divide and conquer (D&C) by implementing WebSphere clustering. Running many JVMs, or cluster members, each with a smaller Web container, will prove beneficial when compared to a single JVM deployment with a large Web container. 148 IBM WebSphere Portal V6 Self Help Guide

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148
IBM WebSphere Portal V6 Self Help Guide
5.2.5
Web container
The Web container serves to “gate” the amount of incoming HTTP requests. The larger the
number of threads, the higher the number of concurrent requests are allowed to enter the
Web container. At some point, however, the number of concurrent threads being processed
by the Web container can overwhelm its abilities.
Display Caching should be explicitly enabled for the Portal Web container. In addition, if the
WebSphere Dynacache mechanism is going to be utilized by the Portal for Portlet fragment
caching, the enablement of Servlet Caching is a prerequisite.
To view or modify the Web container settings from the WebSphere Application Server
Administrative Console, select
Servers
Application Servers
WebSphere_Portal
Additional Properties
Thread Pools
Web Container
. Table 5-5 shows the default and
recommended settings.
Table 5-5
Web container settings
In terms of Portal performance, an increase in the maximum number of threads can offer an
improvement. However, care should be taken, as increasing the value too high above the
suggested optimum value of 75 threads can lead to greater %CPU and memory usage.
Setting the number of minimum threads equal to the number of maximum threads does not
normally offer any immediate improvement after startup. An examination of a Java thread
dump will fail to show a thread count matching the minimum thread setting immediately after
initialization.
To view or modify the Web container settings from the WebSphere Application Server
Administrative Console, select
Servers
Application Servers
WebSphere_Portal
Additional Properties
Thread Pools
Web Container
. Table 5-6 shows the default and
recommended values.
Table 5-6
Web container settings
Under no circumstances should the “Allow thread allocation beyond maximum thread size”
feature be enabled. Permitting this setting can lead to runaway thread growth. The
WebSphere queuing mechanism is designed to handle burst traffic, and occasional “floods” of
the Web container should subsume relatively quickly in most circumstances.
Parameter
Default value
Recommended value
Enable Servlet Caching
Disabled
Enabled
Parameter
Default value
Recommended value
Minimum Threads
10
55
Maximum Threads
50
75
Is Growable
Disabled
Disabled
Attention:
Our experience tells us that one commonly made mistake is that many
customers increase the maximum thread pool setting beyond the recommended value in
the hope of increasing performance. As this runs the risk of overwhelming the ability of a
single JVM, our advice instead is to divide and conquer (D&C) by implementing
WebSphere clustering. Running many JVMs, or cluster members, each with a smaller Web
container, will prove beneficial when compared to a single JVM deployment with a large
Web container.