Python中如何通过greenlet和gevent实现并发，请提供代码示例解析？

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Greenlet 示例，使用 greenlet 微线程，允许在线程中手动切换，示例1，线程切换：pythonfrom greenlet import greenlet

def test1(x, y): z=gr2.switch(x + y) print(z)

def test2(u): print(u) gr1.switch(42)

gr1=greenlet(test1)gr2=greenlet(test2)gr1.switch()

greenlet示例

greenlet微线程,允许在线程中手动切换

示例1,线程切换

from greenlet import greenlet def test1(x,y): z = gr2.switch(x+y) print(z) def test2(u): print(u) gr1.switch(42) gr1 = greenlet(test1) gr2 = greenlet(test2) gr1.switch("hello",'world')

gr1和gr2是两个greenlet线程,使用gr1.switch(..)启动gr1,gr1执行test1,切换到gr2,gr2执行test2打印helloworld,然后切换回gr1,z获取

到返回值42,并打印.

执行顺序为:

gr1.switch("hello",'world') -> test1('hello','world')->

gr2.switch('helloword')->test2('helloworld')->print('helloworld')

->gr1.switch(42)->z=42->print(42)

打印结果:

helloworld
42

示例2

from greenlet import greenlet def eat(name): print('%s eat 1' %name) g2.switch('egon') print('%s eat 2' %name) g2.switch() def play(name): print('%s play 1' %name) g1.switch() print('%s play 2' %name) g1=greenlet(eat) g2=greenlet(play) g1.switch('egon')#可以在第一次switch时传入参数，以后都不需要

g1.switch('egon')#可以在第一次switch时传入参数，以后都不需要

gevent

gevent基于greenlet,遇到IO操作自动切换,IO操作比如网络请求,或使用 gevent.sleep(0)强制切换.

示例1

import gevent def func1(): print("start func1") gevent.sleep(1) print("end func1") def func2(): print("start func2") gevent.sleep(1) print("end func2") gevent.joinall( [ gevent.spawn(func1), gevent.spawn(func2) ] )

执行结果:

start func1
start func2
end func1
end func2
``

示例2: gevent使用monkey对所有系统自带的IO操作打patch

```python from gevent import monkey;monkey.patch_all() import gevent import time def eat(): print('eat food 1') time.sleep(2) # 会自动的跳转到play print('eat food 2') def play(): print('play 1') time.sleep(1) # 会自动的跳转到eat print('play 2') g1=gevent.spawn(eat) g2=gevent.spawn(play) gevent.joinall([g1,g2]) print('end')

执行结果

eat food 1
play 1
play 2
eat food 2
end

示例3,发送请求

from gevent import monkey; monkey.patch_all() import gevent import requests def f(url): print('GET: %s' % url) resp = requests.get(url) data = resp.text print('%d bytes received from %s.' % (len(data), url)) gevent.joinall([ gevent.spawn(f, 'www.python.org/'), gevent.spawn(f, 'www.yahoo.com/'), gevent.spawn(f, 'github.com/'), gevent.spawn(f, 'github.com/'), gevent.spawn(f, 'github.com/'), gevent.spawn(f, 'github.com/'), gevent.spawn(f, 'github.com/'), ])

示例4:使用gevent的socket替代系统的socket

import gevent from gevent import socket urls = ['www.baidu.com', 'www.163.com', 'www.qq.com'] jobs = [gevent.spawn(socket.gethostbyname, url) for url in urls] gevent.joinall(jobs, timeout=2) print([job.value for job in jobs]) 或使用patch_socket() from gevent import monkey; monkey.patch_socket() import gevent def f(n): for i in range(n): print(gevent.getcurrent(), i) gevent.sleep(0) # 不加的话不会交替执行 g1 = gevent.spawn(f, 5) g2 = gevent.spawn(f, 5) g3 = gevent.spawn(f, 5) g1.join() g2.join() g3.join()

示例5:队列中使用gevent.sleet(0)强制切换到其他线程

import gevent from gevent.queue import Queue def func(): for i in range(10): print("int the func") q.put(f"test{i}") gevent.sleep(0) def func2(): for i in range(10): print("int the func2") res = q.get() print("--->",res) q = Queue() gevent.joinall( [ gevent.spawn(func2), gevent.spawn(func), ] )

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持易盾网络。