很多场景为了不阻塞，都需要异步回调机制。这是一个简单的例子。

python的多线程异步常用到queue和threading模块

#!/usr/bin/env python  # -*- coding: UTF-8 -*-      import logging  import queue  import threading      def func_a(a, b):      return a + b      def func_b():      pass      def func_c(a, b, c):      return a, b, c      # 异步任务队列  _task_queue = queue.Queue()      def async_call(function, callback, *args, **kwargs):      _task_queue.put({          'function': function,          'callback': callback,          'args': args,          'kwargs': kwargs      })      def _task_queue_consumer():      """      异步任务队列消费者      """      while True:          try:              task = _task_queue.get()              function = task.get('function')              callback = task.get('callback')              args = task.get('args')              kwargs = task.get('kwargs')              try:                  if callback:                      callback(function(*args, **kwargs))              except Exception as ex:                  if callback:                      callback(ex)              finally:                  _task_queue.task_done()          except Exception as ex:              logging.warning(ex)      def handle_result(result):      print(type(result), result)      if __name__ == '__main__':      t = threading.Thread(target=_task_queue_consumer)      t.daemon = True      t.start()          async_call(func_a, handle_result, 1, 2)      async_call(func_b, handle_result)      async_call(func_c, handle_result, 1, 2, 3)      async_call(func_c, handle_result, 1, 2, 3, 4)          _task_queue.join()