The product provides plug-ins for several Web server brands and
versions. If you are running your Web server on a non-IBM® i platform, see the product documentation
for performance tuning information.
About this task
For additional information,
refer to Chapter 6 of the Performance Capabilities Reference Manual. This
manual is available in the Performance Management Resource Library.
The IBM HTTP
Server (powered by Apache) is a multi-process, multi-threaded server. To tune
this Web server:
Procedure
- Enable the access logs. The access logs record all incoming
HTTP requests. Logging can degrade performance even though logging occurs
in a separate process from the Web server function.
By default, the access
log is disabled. It is recommended that you do not enable the access logs
unless you need a record of all incoming HTTP requests.
To enable the
access logs:
- Open the IBM HTTP Server httpd.conf file, located in the /QIBM/ProdData/HTTPA/conf
directory.
- Search for lines with the text CustomLog.
- Remove the hash mark (#) at the beginning of the line to enable
a custom access log.
- Save and close the httpd.conf file.
- Stop and restart the IBM HTTP Server.
- Change the ThreadsPerChild directive setting. The ThreadsPerChild
directive specifies the maximum number of concurrent client requests that
the server processes at any time. The Web server uses one thread for each
request that it processes. The value specified for this directive does not
represent the number of active clients.
To change the ThreadsPerChild directive
setting:
- Open the IBM HTTP Server httpd.conf file, located in the /QIBM/ProdData/HTTPA/conf
directory.
- Search for the ThreadsPerChild directive.
- Change the setting. The default value is 40. It is
recommended that you either use the default value or increase the value if
you need to increase the number of concurrent client requests that the server
can process at any time. You should not decrease the setting of this directive.
- Save and close the httpd.conf file.
- Stop and restart the IBM HTTP Server.
- Change the ListenBackLog directive setting. This directive
specifies the length of the pending connections queue. When several clients
request connections to the IBM HTTP Server, and all threads are in use, a queue
is created to hold additional client requests.
If you use the default Fast
Response Cache Accelerator (FRCA) feature, the value specified for the ListenBackLog
directive is ignored, because FRCA uses its own internal queue.
To
change the ListenBackLog directive setting:
- Open the IBM HTTP Server httpd.conf file, located in the /QIBM/ProdData/HTTPA/conf
directory.
- Search for the ListenBackLog directive.
- Change the setting. For the IBM HTTP Server 1.3.26, the default setting
is 1024 if FRCA is enabled, and 511 if FRCA disabled. It is recommended that
you use these default values.
- Save and close the httpd.conf file.
- Stop and restart the IBM HTTP Server.