Java - DTracing Java

   These scripts trace the JVM, and require the Java hotspot provider which
   was shipped with Java starting with version 1.6.0.

   Some of these scripts measure method and object events, and require
   the Java process to be run using the "+ExtendedDTraceProbes" flag.
   For example,

	java -XX:+ExtendedDTraceProbes classfile

   The ExtendedDTraceProbes flag is not on by default to avoid the additional
   overhead for maintaining these additional probes. When this flag is
   enabled, the JVM may execute slightly slower than before; when the probes
   are also enabled (especially method probes), the JVM may execute
   significantly slower.