携程，

》》》》》携程greenlet模块

 1 from greenlet import greenlet
 2 def test1():
 3     print(15)
 4     gr1.switch()
 5     print(16)
 6     gr1.switch()
 7 def test2():
 8     print(25)
 9     gr2.switch()
10     print(26)
11     gr2.switch()
12 gr2 = greenlet(test1) #启动一个携程
13 gr1 = greenlet(test2)
14 # gr2.switch()
15 gr2.switch()

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1，注意开关的顺序所造成的不同结果

》》》》》yield

 1 import time
 2 def consumer(name):#消费者
 3     print('start eat baozi')
 4     while True:
 5         new_baozi = yield#阻塞有包子就吃没有就等待
 6         print("[%s] is eatting %s baozi"%(name,new_baozi))
 7         
 8 def producer():#生产者
 9     r = con1.__next__()
10     r = con2.__next__()
11     n = 0
12     while n < 5:
13         n += 1
14         con1.send(n)
15         con2.send(n)
16         time.sleep(1)
17         print("生产%s包子 "%n)
18         
19 if __name__ =='__main__':
20     con1 = consumer("c1")
21     con2 = consumer("c2")
22     p = producer()

View Code

1,生产者消费者模型，yield阻塞等待

》》》》》爬虫

 1 from gevent import monkey;
 2 import gevent
 3 from urllib.request import urlopen
 4 import time
 5 
 6 def f(url):
 7     print("get : %s" % url)
 8     resp = urlopen(url)
 9     data = resp.read()
10     print("%s bytes recv from %s"%(len(data) , url))
11 
12 time_start = time.time()
13 gevent.joinall([
14     gevent.spawn(f,'https://www.python.org/'),
15     gevent.spawn(f, 'https://www.yahoo.com/'),
16     gevent.spawn(f, 'https://github.com/'),
17 ])
18 
19 print("同步cost",time.time() - time_start)

同步执行的爬虫

 1 __author__ = "Alex Li"
 2 
 3 from gevent import monkey;
 4 
 5 # monkey.patch_all()
 6 import gevent
 7 from  urllib.request import urlopen
 8 import time
 9 
10 def f(url):
11     print('GET: %s' % url)
12     resp = urlopen(url)
13     data = resp.read()
14     print('%d bytes received from %s.' % (len(data), url))
15 
16 urls = [ 'https://www.python.org/',
17          'https://www.yahoo.com/',
18          'https://github.com/'
19          ]
20 
21 
22 async_time_start = time.time()
23 gevent.joinall([
24     gevent.spawn(f, 'https://www.python.org/'),
25     gevent.spawn(f, 'https://www.yahoo.com/'),
26     gevent.spawn(f, 'https://github.com/'),
27 ])
28 print("异步cost",time.time()-async_time_start )

async爬虫