When running the current JDWP implementation under the hotspot vm, the following message is printed at startup.

HotSpot VM warning: Ignoring breakpoint on java.lang.Thread.resume

The breakpoint on Thread.resume is an important part of the JDWP implementation that helps avoid race conditions when suspending and resuming multiple threads. As I recall, this was done during Hotspot JVMDI development for performance reasons, but it really should be removed in the production release. (And if there are performance problems with setting a breakpoint at VM startup, they should be addressed as well.)