This book is one step in achieving real-time system JVM by studying the lock mechanism in free source JVM called KaffeJVM and modifying the code to have the locking respect priority locking rather than first come first served locking, which is the case in existing commercial JVM's. The results achieved by this study were made and a real-time system JVM ( in locking objects) were successful and simulation of several tests were made to insure this goal. The work can be extended to different areas of the real-time system Java specification.