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Custom Web container settings
In addition to the generic parameters just discussed, there exists a number of custom
parameters that can be further defined to improve the characteristics of the Web container.
Among these, control of a Web container's Listen Backlog queue is achieve able through the
use of the MaxConnectBacklog parameter. If there are more connection requests than
available Web container threads, then connections start to backlog, waiting for threads to be
freed. If the maximum number of backlog connections is reached, new connections will be
refused. Increasing the MaxConnectBacklog queue can extend the number requests queued
in the network layer. However, the full implication of increasing the MaxConnectBacklog
queue should be understood, as an increased value can effectively lead to latency problems
with the WebSphere plug-in resident in the chosen Web server not immediately detecting that
an application server has ceased operation (either through a deliberate stoppage or on the
occasion of a JVM crash). Choosing the most appropriate value is therefore dependant on the
results you wish to achieve.
To view or modify the Web Container Custom Property Settings from the WebSphere
Application Server Administrative Console, select Servers → Application Servers →
WebSphere_Portal → Additional Properties → Thread Pools → Web Container →
Custom Properties. Table 5-7 shows the default and recommended values.
Table 5-7 Web container custom property settings
Parameter
MaxConnectBacklog
ConnectionIOTimeOut
MaxKeepAliveConnections
MaxKeepAliveRequests
ConnectionKeepAliveTimeOut
The ConnectionIOTimeOut setting can be used to override the maximum time in seconds that
a Web container waits when trying to read or write data during a request. It serves to prevent
a worst case scenario of runaway connections not timing out. A default value of five seconds
is assumed without explicitly setting the parameter.
The remaining three additional custom parameters share the same function as their
counterparts found in the httpd.conf configuration of the IBM HTTP Server (IHS).
5.2.6 Data source tuning
The size and behavior for database connection pools managed by WebSphere are
maintained by their associated data source configurations. The minimum and maximum pool
settings should be set appropriately. Since large pool sizes imply greater resource usage and
more contention due to increased concurrency, the best performance is typically achieved
with small to moderate connection pool sizes. If performance is at a premium, then the
settings for the WebSphere Portal Server data sources should be chosen with care. It is
important to understand that increasing the maximum number of connections permitted by a
datasource runs the risk of overwhelming the associated database. In terms of performance
tuning, an increase can also lead to greater resource usage and more contention due to
increased concurrency.
Default value
512
5
90%
100
120
Chapter 5. WebSphere Portal runtime and services
Recommended value
128
No adjustment
No adjustment
No adjustment
No adjustment
149
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Troubleshooting
