Add a profiler for RDD `id`

def add_profiler(self, id, profiler):
        """ Add a profiler for RDD `id` """
        if not self.profilers:
            if self.profile_dump_path:
                atexit.register(self.dump_profiles, self.profile_dump_path)
            else:
                atexit.register(self.show_profiles)

        self.profilers.append([id, profiler, False])