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爬虫——生产者消费者

2018-09-29 03:59:22来源：博客园阅读 ()

结构

生产者生成网址并放入队列

多个消费者从队列中取出网址

 1 from queue import Queue
 2 import time, threading, requests
 3 
 4 url_base = 'http://www.qiushibaike.com/8hr/page/{}/'
 5 header = {}
 6 
 7 def load_data():
 8     return [url_base.format(i) for i in [1, 3, 6, 7]]
 9 
10 #生产者
11 def produce(q):
12     index = 0
13     data = load_data()
14     while True:
15         if index < len(data):
16             q.put(data[index])
17             index += 1
18 
19 #消费者
20 def consume(q):
21     while True:
22         download_url = q.get()
23         # requests.get(download_url,headers=header)
24         print('thread is {} content is {}'.format(threading.current_thread(), download_url))
25 
26 def main():
27     q = Queue(4)
28     p1 = threading.Thread(target=produce, args=[q])
29     c1 = threading.Thread(target=consume, args=[q])
30     c2 = threading.Thread(target=consume, args=[q])
31     p1.start()
32     c1.start()
33     c2.start()
34 
35 if __name__ == '__main__':
36     main()

类

爬虫类需要继承多线程类

初始化方法需要继承父类初始化方法

创建对象，直接start就会调用类中run方法

 1 # class ConsumeSpider(threading.Thread):
 2 #     def __init__(self):
 3 #         super().__init__()
 4 #         pass
 5 #
 6 #     def run(self):
 7 #         pass
 8 #
 9 # c3 = ConsumeSpider()
10 # c3.start()

协程

协程(coroutine)：轻量级的线程，不存在上下文切换，能在多个任务之间调度的多任务方式，可以使用yield实现

 1 import time, threading
 2 
 3 def task_1():
 4     while True:
 5         print('-----1-----', threading.current_thread())
 6         time.sleep(1)
 7         yield
 8 
 9 
10 def task_2():
11     while True:
12         print('-----2-----', threading.current_thread())
13         time.sleep(1)
14         yield
15 
16 
17 def main():
18     t1 = task_1()
19     t2 = task_2()
20     while True:
21         next(t1)
22         next(t2)
23 
24 
25 if __name__ == '__main__':
26     main()
27