The jstat tool is used to obtain a variety of statistical information from the JVM, much like the vmstat utility that can be used to obtain CPU utilization information from the operating system. The general manner to invoke it is as follows:
jstat {type} {processID} {interval}
The {interval} option specifies the length of time in milliseconds between lines of output. The {processID} option specifies the process ID of the JVM used to run the Directory Server, which can be obtained by running jps as mentioned previously. The {type} option specifies the type of output that should be provided. Some of the most useful types include:
  • -class – Provides information about class loading and unloading.
  • -compile – Provides information about the activity of the JIT complex.
  • -printcompilation – Provides information about JIT method compilation.
  • -gc – Provides information about the activity of the garbage collector.
  • -gccapacity – Provides information about memory region capacities.