You may want to change the JVM (Java Virtual Machine) to a version other than the one that shipped with the installation of ColdFusion MX. This TechNote describes how to change the JVM when using JRun. If you are using another application server, please consult their respective documentation.

The following table lists the default JVM version changes that shipped with ColdFusion MX:

ColdFusion MX Release JVM Version
6,0,48097 Sun 1.3.1_03-b0
6,1,0,63958 Sun 1.4.2-b28
7,0,0,91690 Sun 1.4.2_05
7,0,2,142559 Sun 1.4.2_09-b05
ColdFusion 8 Release JVM Version
8,0,0,176276 Sun 1.6.0_01-b06


Note: For compliance with the 2005 US DST (Daylight Savings Time) change, all versions of ColdFusion MX require changing the JVM. See 2005 US DST TechNote for more information. ColdFusion 8 is 2005 DST compliant.

Please consult the ColdFusion MX 7.0.2 and ColdFusion 8 System Requirements for information on currently supported JVM versions.

Run the following command from the jre/bin directory to confirm the JVM version: java -version.

In order to change the JVM, you must download and install one of the supported JDK/SDKs from the Sun Developer Network at http://java.sun.com/j2se/. ColdFusion requires the Java HotSpot Server virtual machine (jre/bin/server/jvm.dll), which is not available with the JRE download.

JRun stores startup parameters in a file named jvm.config located in the cf_root/runtime/bin or jrun_root/bin directory depending on how you installed ColdFusion. The initial jvm.config you get at install is your default configuration for all servers unless you specify a '-config' parameter when starting JRun. If you do specify the '-config' parameter, JRun will start using the specified parameter file. The below instructions will use the term jvm.config as it relates to all of your parameters files.

The jvm.config has an argument called "java.home." The "java.home" argument accepts a value of the path to your JRE (Java Runtime Environment). For example: java.home=C:/CFusionMX7/runtime/jre

When you change your JVM, this argument must reflect the path to your new JRE. For example: java.home=C:/j2sdk1.4.2_11/jre

If no java.home is specified, the JRun start program will search for a VM on your OS as documented in the default jvm.config file. If you use a defined java.home in the jvm.config, any dependency on the JAVA_HOME environment variable will be removed.

Updating the JVM from the Administrator (Server ConfigurationOnly)

The ColdFusion Server configuration has an option in the ColdFusion Administrator called "Java and JVM." You may change the path to the JRE by changing the value of "Java Virtual Machine Path" (see below).

Whether you change the JVM path via the ColdFusion Administrator (Server configuration only) or by editing the jvm.config file, you must restart ColdFusion after the changes have been made.

Note: Always make a backup copy of your jvm.config before making any changes, either manually or via the ColdFusion Administrator.

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