python note 34 并发

1、socket发送请求

import socket
import requests

# 方式一
ret = requests.get('https://www.baidu.com/s?wd=alex')

# 方式二
client = socket.socket()
client.connect(('www.baidu.com',80))
client.sendall(b'GET /s?wd=alex HTTP/1.0
host:www.baidu.com

')
chunk_list = []
while True:
    chunk = client.recv(8096)
    if not chunk:
        break
    chunk_list.append(chunk)

body = b''.join(chunk_list)
print(body.decode('utf-8'))

2、解决并发

单线程
import socket
import requests

key_list = ['alex','db','sb']
for item in key_list:
    ret = requests.get('https://www.baidu.com/s?wd=%s' %item)

3、setblocking(False)将原来阻塞的位置变成非阻塞

import socket

client = socket.socket()
client.setblocking(False) # 将原来阻塞的位置变成非阻塞（报错）
# 百度创建连接: 阻塞

try:
    client.connect(('www.baidu.com',80)) # 执行了但报错了
except BlockingIOError as e:
    pass

# 检测到已经连接成功

# 问百度我要什么？
client.sendall(b'GET /s?wd=alex HTTP/1.0
host:www.baidu.com

')

# 我等着接收百度给我的回复
chunk_list = []
while True:
    chunk = client.recv(8096) # 将原来阻塞的位置变成非阻塞（报错）
    if not chunk:
        break
    chunk_list.append(chunk)

body = b''.join(chunk_list)
print(body.decode('utf-8'))

4、协程

import greenlet

def f1():
    print(11)
    gr2.switch()
    print(22)
    gr2.switch()

def f2():
    print(33)
    gr1.switch()
    print(44)

# 协程 gr1
gr1 = greenlet.greenlet(f1)
# 协程 gr2
gr2 = greenlet.greenlet(f2)

gr1.switch()