* interrupting thread. In theory, interruptTask() should be very fast, but due to
         * InterruptibleChannel and JavaLangAccess.blockedOn(Thread, Interruptible), it isn't
         * predictable what work might be done. (e.g., close a file and flush buffers to disk). To
         * protect ourselves from this, we park ourselves and tell our interrupter that we did so.
         */