Python程序中的协程操作-gevent模块
一、安装
安装：pip3 install gevent
二、Gevent模块介绍
Gevent 是一个第三方库，可以轻松通过gevent实现并发同步或异步编程，在gevent中用到的主要模式是Greenlet，它是以C扩展模块形式接入Python的轻量级协程。 Greenlet全部运行在主程序操作系统进程的内部，但它们被协作式地调度。
2.1 用法介绍
g1=gevent.spawn(func,1,,2,3,x=4,y=5)：创建一个协程对象g1，spawn括号内第一个参数是函数名，如eat，后面可以有多个参数，可以是位置实参或关键字实参，都是传给函数eat的
g2=gevent.spawn(func2)
g1.join()：等待g1结束
g2.join()：等待g2结束
上述两步合作一步：gevent.joinall([g1,g2])
g1.value：拿到func1的返回值
2.2 例：遇到io主动切换
import gevent,time
def eat(name):
print('%s eat 1' % name)
gevent.sleep(2)
print('%s eat 2' % name)
def play(name):
print('%s play 1' % name)
gevent.sleep(1)
print('%s play 2' % name)
start = time.time()
g1 = gevent.spawn(eat, 'randy')
g2 = gevent.spawn(play, name='randy')
g1.join()
g2.join()
# 或者gevent.joinall([g1,g2])
print('主')
end = time.time()
print(end-start)
randy eat 1
randy play 1
randy play 2
randy eat 2
主
2.0066120624542236
上例gevent.sleep(2)模拟的是gevent可以识别的io阻塞，而time.sleep(2)或其他的阻塞，gevent是不能直接识别的需要用下面一行代码，打补丁，就可以识别了。
from gevent import monkey;monkey.patch_all()必须放到被打补丁者的前面，如time，socket模块之前。
或者我们干脆记忆成：要用gevent，需要将from gevent import monkey;monkey.patch_all()放到文件的开头。
from gevent import monkey;monkey.patch_all()
import gevent
import time
def eat():
print('eat food 1')
time.sleep(2)
print('eat food 2')
def play():
print('play 1')
time.sleep(1)
print('play 2')
g1=gevent.spawn(eat)
g2=gevent.spawn(play)
gevent.joinall([g1,g2])
print('主')
eat food 1
play 1
play 2
eat food 2
主
2.0046091079711914
我们可以用threading.current_thread().getName()来查看每个g1和g2，查看的结果为DummyThread-n，即假线程
2.3 查看threading.current_thread().getName()
from gevent import monkey;
monkey.patch_all()
import threading
import gevent
import time
def eat():
print(threading.current_thread().getName())
print('eat food 1')
time.sleep(2)
print('eat food 2')
def play():
print(threading.current_thread().getName())
print('play 1')
time.sleep(1)
print('play 2')
start = time.time()
g1 = gevent.spawn(eat)
g2 = gevent.spawn(play)
gevent.joinall([g1, g2])
print('主')
end = time.time()
print(end - start)
DummyThread-1
eat food 1
DummyThread-2
play 1
play 2
eat food 2
主
2.004635810852051
三、Gevent之同步与异步
ffrom gevent import spawn, joinall, monkey;
monkey.patch_all()
import time
def task(pid):
"""
Some non-deterministic task
"""
time.sleep(0.5)
print('Task %s done' % pid)
def synchronous(): # 同步
for i in range(10):
task(i)
def asynchronous(): # 异步
g_l = [spawn(task, i) for i in range(10)]
joinall(g_l)
print('DONE')
if __name__ == '__main__':
syn_start = time.time()
print('Synchronous:')
synchronous()
syn_end = time.time()
print(f'syn:{syn_end - syn_start}')
asy_start = time.time()
print('Asynchronous:')
asynchronous()
asy_end = time.time()
print(f'asy:{asy_end - asy_start}')
# 上面程序的重要部分是将task函数封装到Greenlet内部线程的gevent.spawn。
# 初始化的greenlet列表存放在数组threads中，此数组被传给gevent.joinall 函数，
# 后者阻塞当前流程，并执行所有给定的greenlet任务。执行流程只会在 所有greenlet执行完后才会继续向下走。
Synchronous:
Task 0 done
Task 1 done
Task 2 done
Task 3 done
Task 4 done
Task 5 done
Task 6 done
Task 7 done
Task 8 done
Task 9 done
syn:5.014581918716431
Asynchronous:
Task 0 done
Task 1 done
Task 2 done
Task 3 done
Task 4 done
Task 5 done
Task 6 done
Task 7 done
Task 8 done
Task 9 done
DONE
asy:0.5006606578826904
四、Gevent之应用
通过gevent实现单线程下的socket并发
注意：from gevent import monkey;monkey.patch_all()一定要放到导入socket模块之前，否则gevent无法识别socket的阻塞。
4.1 服务端
from gevent import monkey;monkey.patch_all()
from socket import *
import gevent
#如果不想用money.patch_all()打补丁,可以用gevent自带的socket
# from gevent import socket
# s=socket.socket()
def server(server_ip,port):
s=socket(AF_INET,SOCK_STREAM)
s.setsockopt(SOL_SOCKET,SO_REUSEADDR,1)
s.bind((server_ip,port))
s.listen(5)
while True:
conn,addr=s.accept()
gevent.spawn(talk,conn,addr)
def talk(conn,addr):
try:
while True:
res=conn.recv(1024)
print('client %s:%s msg: %s' %(addr[0],addr[1],res))
conn.send(res.upper())
except Exception as e:
print(e)
finally:
conn.close()
if __name__ == '__main__':
server('127.0.0.1',8080)
4.2 客户端
from socket import *
client=socket(AF_INET,SOCK_STREAM)
client.connect(('127.0.0.1',8080))
while True:
msg=input('>>: ').strip()
if not msg:continue
client.send(msg.encode('utf-8'))
msg=client.recv(1024)
print(msg.decode('utf-8'))
4.3 多线程并发多个客户端
from threading import Thread
from socket import *
import threading
def client(server_ip,port):
c=socket(AF_INET,SOCK_STREAM) #套接字对象一定要加到函数内，即局部名称空间内，放在函数外则被所有线程共享，则大家公用一个套接字对象，那么客户端端口永远一样了
c.connect((server_ip,port))
count=0
while True:
c.send(('%s say hello %s' %(threading.current_thread().getName(),count)).encode('utf-8'))
msg=c.recv(1024)
print(msg.decode('utf-8'))
count+=1
if __name__ == '__main__':
for i in range(500):
t=Thread(target=client,args=('127.0.0.1',8080))
t.start()
4.4 爬虫
from gevent import monkey;
monkey.patch_all()
import gevent
import requests
import time
def get_page(url):
print('GET: %s' % url)
response = requests.get(url)
if response.status_code == 200:
print('%d bytes received from %s' % (len(response.text), url))
start_time = time.time()
gevent.joinall([
gevent.spawn(get_page, 'https://www.python.org/'),
gevent.spawn(get_page, 'https://www.yahoo.com/'),
gevent.spawn(get_page, 'https://github.com/'),
])
stop_time = time.time()
print('run time is %s' % (stop_time - start_time))