03 September 2009

Switching Between JRockit and Sun JDK with WebLogic Server

Need to swap between JRockit and the Sun JDK when starting your WebLogic Server instance?

Looking at the start scripts $DOMAIN_HOME/bin/setDomainEnv.cmd, I just realized that this operational task is basically taken care of in the scripts we have.

To swap between the Sun JDK and JRockit to launch a WLS instance, all you need to do is set the JAVA_VENDOR environment variable to either "Sun" or "Oracle" and the scripts will take of launching WLS using the specified JDK.

Snippets from setDomainEnv.cmd:
set BEA_JAVA_HOME=d:\wls1031\jrockit_160_05_R27.6.2-20
set SUN_JAVA_HOME=d:\wls1031\jdk160_11

if "%JAVA_VENDOR%"=="Oracle" (
) else (
if "%JAVA_VENDOR%"=="Sun" (
) else (
set JAVA_HOME=d:\wls1031\jdk160_11

Where JAVA_HOME is then used by startWebLogic.cmd script when it launches the WLS instance to identify the JDK to use.

Snippets from startWebLogic.cmd
%JAVA_HOME%\bin\java %JAVA_VM% %MEM_ARGS% 

With this information at hand, then switching between the two different JDKs is as simple as setting an environment variable before launching WebLogic Server.

Using JRockit:
>set JAVA_VENDOR=Oracle
d:\wls1031\JROCKI~1.2-2\bin\java -jrockit -Xms512m -Xmx512m -Dweblogic.Name=AdminServer ...

And just as easy to switch back to Sun. Note here that you could just unset the JAVA_HOME environment variable, which will set the script to use whatever default was configured when the domain was created.

Using Sun JDK:
d:\wls1031\JDK160~1\bin\java -client -Xms256m -Xmx512m -Dweblogic.Name=AdminServer ...

1 comment:

Pravin Jose said...

Thanks! a lot Buttso for the blog. I was able to switch between Sun JDK and JRockit by using JAVA_VENDOR parameter.

This is very elegant approach.Thanks! for pointing this out.

Initially I was thinking of modifying JAVA_HOME variable in multiple files for switching JDK which is no longer required.