self.sched.queue[:] = []                    

    def _run(self):
        # Low-level run method to do the actual scheduling loop.
        while self.running:
            try:
                self.sched.run()
            except Exception as x:
                print >>sys.stderr, "ERROR DURING SCHEDULER EXECUTION",x
                print >>sys.stderr, "".join(
                    traceback.format_exception(*sys.exc_info()))
                print >>sys.stderr, "-" * 20
            # queue is empty; sleep a short while before checking again
            if self.running:
                time.sleep(5)

        self.args=args
        self.kw=kw

    def __call__(self, schedulerref):
        """Execute the task action in the scheduler's thread."""
        try:
            self.execute()
        except Exception as x:
            self.handle_exception(x)
        self.reschedule(schedulerref())

    def reschedule(self, scheduler):
        """This method should be defined in one of the sub classes!"""
        raise NotImplementedError("You're using the abstract base class 'Task',"
            " use a concrete class instead")

            self.reschedule(schedulerref())

        def threadedcall(self):
            # This method is run within its own thread, so we have to
            # do the execute() call and exception handling here.
            try:
                self.execute()
            except Exception as x:
                self.handle_exception(x)

    class ThreadedIntervalTask(ThreadedTaskMixin, IntervalTask):
        """Interval Task that executes in its own thread."""
        pass

    class ThreadedSingleTask(ThreadedTaskMixin, SingleTask):

        def __call__(self, schedulerref):
            """Execute the task action in its own process."""
            pid = os.fork()
            if pid == 0:
                # we are the child
                try:
                    self.execute()
                except Exception as x:
                    self.handle_exception(x)
                os._exit(0)
            else:
                # we are the parent
                self.reschedule(schedulerref())