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" (
set JAVA_HOME=%BEA_JAVA_HOME%
) else (
if "%JAVA_VENDOR%"=="Sun" (
set JAVA_HOME=%SUN_JAVA_HOME%
) else (
set JAVA_VENDOR=Sun
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% 
-Dweblogic.Name=%SERVER_NAME% 
-Djava.security.policy=%WL_HOME%\server\lib\weblogic.policy 
%JAVA_OPTIONS% 
%PROXY_SETTINGS% 
%SERVER_CLASS%

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
>startWebLogic.cmd
...
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:

>set JAVA_VENDOR=Sun
>startWebLogic.cmd
...
d:\wls1031\JDK160~1\bin\java -client -Xms256m -Xmx512m -Dweblogic.Name=AdminServer ...