多线程 VS 多进程（三）

	def clock(interval):

	    while True:

	        print("The time is %s" % ctime())

	        sleep(interval)

	if __name__ == '__main__':

	    p = multiprocessing.Process(target=clock, args=(5, ))

	    p.start()

	    while True:

	        print("sleeping......")

	        sleep(1)

    ```

	    sleeping......

		The time is Tue Aug 13 19:47:41 2019

		sleeping......

		sleeping......

		sleeping......

		sleeping......

		sleeping......

		The time is Tue Aug 13 19:47:46 2019

		sleeping......

		sleeping......

		sleeping......

		sleeping......

		...

- 派生子类，案例20
    ```python
    import multiprocessing
	from time import sleep, ctime
	

	class ClockProcess(multiprocessing.Process):

	    '''

	    两个函数比较重要

	    1. init构造函数
	    2. run
	    '''
	    def __init__(self, interval):
	        super(ClockProcess, self).__init__()
	        self.interval = interval
	    def run(self):
	        while True:
	            print("The time is %s" % ctime())
	            sleep(self.interval)
	

	if __name__ == '__main__':

	    p = ClockProcess(3)

	    p.start()

    ```

	    The time is Tue Aug 13 19:48:49 2019

		The time is Tue Aug 13 19:48:52 2019

		The time is Tue Aug 13 19:48:55 2019

		The time is Tue Aug 13 19:48:58 2019

		The time is Tue Aug 13 19:49:01 2019

		The time is Tue Aug 13 19:49:04 2019

		...

	def info(title):

	    print(title)

	    print("module name:", __name__)

	    # 得到父亲进程的id

	    print("parent process:", os.getppid())

	    # 得到本身进程的id

	    print("process id:", os.getpid())

	def f(name):

	    info('function f')

	    print('hello', name)

	if __name__ == '__main__':

	    info('main line')

	    p = Process(target=f, args=('bob', ))

	    p.start()

	    p.join()

    ```

	    main line

		module name: __main__

		parent process: 11900

		process id: 18832

		function f

		module name: __mp_main__

		parent process: 18832

		process id: 20868

		hello bob

	def consumer(input_q):

	    print("Into consumer:", ctime)

	    while True:

	        # 处理项

	        item = input_q.get()

	        print('pull', item, 'out of q')

	        input_q.task_done()  # 发出信号通知任务完成

	    print("Out of consumer:", ctime()) ## 此句未执行，因为q.join()收集到四个task_done()信号后，主进程启动，未等到print此句完成，程序就结束了

	def producer(sequence, output_q):

	    print("Into procuder:", ctime())

	    for item in sequence:

	        output_q.put(item)

	        print('put', item, 'into q')

	    print('Out of procuder', ctime())

	# 建立进程

	if __name__ == '__main__':

	    q = multiprocessing.JoinableQueue()

	    # 进行消费者进程

	    cons_p = multiprocessing.Process(target=consumer, args=(q, ))

	    cons_p.daemon = True

	    cons_p.start()

	    # 生产多个项，sequence代表要发送给消费者的项序列

	    # 在实践中，这可能是生成器的输出或通过一些其他地方生产出来

	    sequence = [1, 2, 3, 4]

	    producer(sequence, q)

	    # 等待所有项被处理

	    q.join()

    ```

	    Into procuder: Tue Aug 13 19:50:38 2019

		put 1 into q

		put 2 into q

		put 3 into q

		put 4 into q

		Out of procuder Tue Aug 13 19:50:38 2019

		Into consumer: <built-in function ctime>

		pull 1 out of q

		pull 2 out of q

		pull 3 out of q

		pull 4 out of q

- 队列中哨兵的使用，案例23
    ```python
    import multiprocessing
	from time import ctime
	

	# 设置哨兵问题

	def consumer(input_q):

	    print("Into consumer:", ctime())

	    while True:

	        item = input_q.get()

	        if item is None:

	            break

	        print("pull", item, "out of q")

	    print ("Out of consumer:", ctime()) ## 此句执行完成，再转入主进程

	def producer(sequence, output_q):

	    print ("Into procuder:", ctime())

	    for item in sequence:

	        output_q.put(item)

	        print ("put", item, "into q")

	    print ("Out of procuder:", ctime())

	if __name__ == '__main__':

	    q = multiprocessing.Queue()

	    cons_p = multiprocessing.Process(target = consumer, args = (q,))

	    cons_p.start()

	    sequence = [1,2,3,4]

	    producer(sequence, q)

	    q.put(None)

	    cons_p.join()

    ```

	    Into procuder: Tue Aug 13 19:51:23 2019

		put 1 into q

		put 2 into q

		put 3 into q

		put 4 into q

		Out of procuder: Tue Aug 13 19:51:23 2019

		Into consumer: Tue Aug 13 19:51:24 2019

		pull 1 out of q

		pull 2 out of q

		pull 3 out of q

		pull 4 out of q

		Out of consumer: Tue Aug 13 19:51:24 2019

- 哨兵的改进，案例24
    ```python
    import multiprocessing
	from time import ctime
	

	def consumer(input_q):

	    print ("Into consumer:", ctime())

	    while True:

	        item = input_q.get()

	        if item is None:

	            break

	        print("pull", item, "out of q")

	    print ("Out of consumer:", ctime())

	def producer(sequence, output_q):

	    for item in sequence:

	        print ("Into procuder:", ctime())

	        output_q.put(item)

	        print ("Out of procuder:", ctime())

	if __name__ == '__main__':

	    q = multiprocessing.Queue()

	    cons_p1 = multiprocessing.Process (target = consumer, args = (q,))

	    cons_p1.start()

	    cons_p2 = multiprocessing.Process (target = consumer, args = (q,))

	    cons_p2.start()

	    sequence = [1,2,3,4]

	    producer(sequence, q)

	    q.put(None)

	    q.put(None)

	    cons_p1.join()

	    cons_p2.join()

    ```

	    Into procuder: Tue Aug 13 19:52:08 2019

		Out of procuder: Tue Aug 13 19:52:08 2019

		Into procuder: Tue Aug 13 19:52:08 2019

		Out of procuder: Tue Aug 13 19:52:08 2019

		Into procuder: Tue Aug 13 19:52:08 2019

		Out of procuder: Tue Aug 13 19:52:08 2019

		Into procuder: Tue Aug 13 19:52:08 2019

		Out of procuder: Tue Aug 13 19:52:08 2019

		Into consumer: Tue Aug 13 19:52:08 2019

		pull 1 out of q

		pull 2 out of q

		pull 3 out of q

		pull 4 out of q

		Out of consumer: Tue Aug 13 19:52:08 2019

		Into consumer: Tue Aug 13 19:52:08 2019

		Out of consumer: Tue Aug 13 19:52:08 2019