Enabling the JIT

The JIT is enabled by default. You can explicitly enable the JIT in a number of different ways.

• Use the -D option on the JVM command line to set the java.compiler property to jitc or j9jit<vm_version>, where <vm_version> is the version number of the VM, as reported by the java -version command but without any punctuation.
  For example, in the following output line, the version is 29:

  IBM J9 VM build 2.9, JRE 9 Linux x86-32 20161114_326069 (JIT enabled, AOT enabled)

  At a prompt, enter one of the following commands:

  java -Djava.compiler=jitc <class>

  java -Djava.compiler=j9jit<vm_version> <class>

• Use the -Xjit option on the JVM command line.
  At a prompt, enter the following command:

  java -Xjit <class>

  Note: If you also specify the -Xint option, which disables the JIT and AOT compilers, the option that appears last in the command takes effect.