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Tuning WebLogic JRockit with WebLogic Server on Linux

# Migrating to WebLogic JRockit with WebLogic Server on Linux

BEA WebLogic JRockit JVM is the default JVM shipped with BEA WebLogic Server. Although there are other JVMs available on the market today that you can use to develop Java applications, BEA Systems recommends that you use WebLogic JRockit JVM as the production JVM for any application deployed on WebLogic Server.

This section describes basic environment changes necessary to migrate to WebLogic JRockit JVM from Sun Microsystems HotSpot JVM or any other third-party JVM. It includes information on the following subjects:

- Additional Migration Information
- Required Changes
- Enabling Core Dumps
- Migration Restrictions
- Migration Support

# Additional Migration Information

The migration tips in this chapter are very similar to those for other operating systems, such as Windows. For more comprehensive migration information than is presented here, please refer to Migrating to WebLogic JRockit in the Migration Guide. Along with detailed migration information, this document also includes a discussion of best coding practices for applications designed to run on WebLogic JRockit and extensive troubleshooting information, both of which are equally germane to Linux users.

# Required Changes

To migrate from HotSpot (or any third-party JVM) to WebLogic JRockit JVM, you need to make the following changes to the files specified.

## Changes to Environment Variables

You need to change the environment variables in `<WEBLOGIC_HOME>\common\bin\commEnv.sh as described here:`

- Set the `JAVA_HOME` environmental variable to the appropriate path; for example:

>     # Set up JAVA HOME
>        JAVA_HOME="C:\bea\jdk141_02"

- Set the `JAVA_VENDOR` environmental variable to `BEA`; for example:

>     # Set up JAVA VENDOR, possible values are
>     # BEA, HP, IBM, Sun ...
>        JAVA_VENDOR=BEA

## Changes to Start-up Scripts

If you are using start-up scripts, remove any Sun- (or other JVM provider) specific options from the start command line (for example, `-hotspot`). If possible, replace them with WebLogic JRockit-specific options; for example, `-jrockit`. Other flags that might need to be changed include `MEM_ARGS` and `JAVA_VM`.

## Changes to config.xml

Change `config.xml` to point the default compiler setting(s) to the WebLogic JRockit `javac` compiler; for example:

>     <Server Name="examplesServer" ListenPort="7001" ConsoleInputEnabled=
>        "false" JavaCompiler="javac" SocketReaderTimeoutMaxMillis=
>        "10"OMEnabled="true">

# Enabling Core Dumps

If you are using Red Hat Enterprise Linux AS/ES/WS 2.1 (32-bit) and want to ensure that a `core`/`javacore` file is created in the working directory in the event WebLogic JRockit crashes, you need to enable core dumps. To do this, set the `ulimit -c` value to something greater than zero, but no greater than a value your filesystem can accommodate; for example, `ulimit -c 10000000`. These values are measured in blocks, with each block equaling one kilobyte. You can set the `ulimit` value either from the command line, in the `*.profile` file, or in a shell script.

# Migration Restrictions

Migration is available only for Intel-based Windows and Linux systems. For a list of supported platforms, please refer to:

http://edocs.bea.com/wljrockit/docs81/certif.html

# Migration Support

Should you experience any problems or find any bugs with an application you have migrated to WebLogic JRockit 8.1, please report it to `support@bea.com`. You should provide as much information as possible about the problem, for example:

- Hardware
- Operating system and its version
- The program you are attempting to migrate
- Stack dumps (if any)
- A small code example that will reproduce the error
- Copies of any `*.dump` files