J2SE 1.4.0 includes an enhanced Java Platform Debugger Architecture that has the following new features.
The Java HotSpotTM virtual machine now uses "full-speed debugging". In the previous version of Java HotSpot, when debugging was enabled, the program executed using only the interpreter. Now, the full performance advantage of Java HotSpot technology is available to programs running with debugging enabled. The improved performance allows long running programs to be more easily debugged. It also allows testing to proceed at full speed and the launch of a debugger to occur on an exception.
A HotSwap feature has been added to allow a class to be updated while under the control of a debugger.
EventRequests now have the capability of specifying an instance filter, which restricts the events generated by the request to those in which the currently executing instance is the object specified.
The Java Platform Debugger Architecture has been extended so that non-Java programming language source, which is translated to Java programming language source, can be debugged in the future.
A request can now be made to control target VM termination notification, allowing clean shutdown synchronization.