- Run with the JIT (Just In Time) compiler active.
In the General Properties
section of the Configuration Tab, ensure that Disable JIT is not selected.
The default is JIT support enabled.
- Do not specify the debug version of the JVM libjava_g in your
libpath. Severe performance degradation is likely when running with the debug
version of the JVM.
- Have Classpath point to only the classes you need (the classes that are
referenced most frequently should be located near the front of the path, if
possible).
In the General Properties section of the Configuration Tab,
enter the Classpath in the text box of the Classpath option.
- Verify the Classpath as part of the Java configuration.
- To speed up JVM initialization and improve server startup time, specify
the following command line arguments in the General JVM Arguments field in
the General Properties section of the Configuration Tab.
-Xquickstart
-Xverify:none
For JDK Version
1.3.1, these options can reduce servant startup time by as much as 40%. However,
they will reduce runtime throughput by about 8%.
- Sometimes poor performance is caused by a missing class. The class loader
will look in it's tables of already loaded classes and if the class is not
found to be already loaded it will search for it. This search process can
cause a high amount of I/O activity to the HFS volumes. To determine if this
is the problem you can collect CTRACE records from the file system. Once you
determine which class is not being found you can repair the problem by providing
the class or by removing the need for it.
Note: Please see the
"Applications" section in the WebSphere Application Server for z/OS V5.0 information
center, access to which can be obtained through the WebSphere for z/OS library
Web site http://www.ibm.com/software/webservers/appserv/zos_os390/library.html
for more information on "Application client troubleshooting tips."