JDK-8274687 will add the following fragment to doPendingTasks() in the JDWP agent:

        /*
         * trackAppResume() (indirectly) aquires handlerLock. For proper lock
         * ordering handlerLock has to be acquired before threadLock.
         */
        debugMonitorExit(threadLock);
        eventHandler_lock();
        debugMonitorEnter(threadLock);

Investigate if this can be improved by hoisting the first monitor exit on threadLock up into the caller threadControl_onEventHandlerExit() such that doPendingTasks() would be called without any locks held.