Specifications

28 IBM System z Personal Development Tool: Volume 3 Additional Topics

The jython script

You can make these changes permanent by creating the following script, in ASCII, in

/u/ibmuser/jvmprop.py

###############################################################################

# Script to set JVM generic arguments to

# -Xjit:optLevel=cold,disableInterpreterProfiling

# to improve startup performance of WebSphere on zPDT images.

# Author: Mitch Johnson

# Organization: IBM Advanced Technical Skills

###############################################################################

import java.lang.System as sys

lineSeparator = sys.getProperty(‘line.separator’)

global AdminApp, AdminConfig

cell=AdminConfig.list(“Cell”)

node=AdminConfig.list(“Node”,cell)

serverList=AdminConfig.list(“Server”,node).split(lineSeparator)

for server in serverList:

serverName=AdminConfig.showAttribute(server,”name”)

print “Updating genericJVMArguments for server: “ + serverName

objID=AdminConfig.getid(“/Server:” + serverName + “/”)

jvmList=AdminConfig.list(“JavaVirtualMachine”,objID).split(lineSeparator)

for jvm in jvmList:

print “Updating JVM generic arguments for “ + jvm

AdminConfig.modify(jvm, [[“genericJvmArguments”,”-Xquickstart

-Xverify:none -Xjit:optLevel=cold,disableInterpreterProfiling”]] )

print AdminConfig.queryChanges()

print AdminConfig.save()

print “Changes saved”

Remember: the above script must be entered in ASCII.

During the configuration of an instance of WebSphere on z/OS the system programmer

specifies an HFS directory where the configuration files reside. We use /u/WebSphere/V6R1

in this example. The WebSphere configuration process populates this structure with the

customized configuration and symbolic links to the WebSphere product code in

/usr/lpp/zWebSphere. The jython script shown above does not connect to an active

WebSphere instance; instead, it makes changes to the configuration files relative to the

directory in which its execution begins. Therefore, our example assumes that the

configuration files are located in directory /u/WebSphere/V6R1.

Go to directory /u/WebSphere/V6R1/AppServer/bin and enter the following command:

./wsadmin.sh -conntype none -f /u/ibmuser/jvmprop.py -lan jython

Another convenient directory could be used; the location of the script is not critical.