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.