使用异步io实现只使用单进程，单线程的socket。处理多个用户的请求。
先简单说明一下select异步io工作原理：
select 是一个跨平台的异步io模型，由于我们计算机的硬盘速度，远远低于我们内存的速度，因此如果同时有多个用户来请求数据时候，io效率就会变得更慢。
而select 是一直不断在监控我们网络接口的。如果我们的服务器网络接收到，一个用户的请求，就会在系统的某个路径下面，生成一个文件描述符，select就是不断的在监控这些文件描述符（即每个用户的连接），如果连接进来了，就会调用内核将这个文件描述符标志位改为ready，从而我们的select就可以操作这文件描述符了。
回到我们的程序上来，异步的socket 使用select 就是一直在循环，不断的去监视文件描述符，当有新的用户来连接时候，直接把新连接的用户保存到一个列表当中。如果循环到不是新的用户则对用户的操作进行处理
socket 服务器端
#!/usr/bin/env python
# _*_ coding:utf-8 _*_
import select
import socket
import sys
import Queue
# Create a TCP/IP socket
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.setblocking(False)
# Bind the socket to the port
server_address = (‘localhost‘, 10000)
print(sys.stderr, ‘starting up on %s port %s‘ % server_address)
server.bind(server_address)
# Listen for incoming connections
server.listen(5)
# Sockets from which we expect to read
inputs = [server]
# Sockets to which we expect to write
outputs = []
message_queues = {}
while inputs:
# Wait for at least one of the sockets to be ready for processing
print(‘\nwaiting for the next event‘)
readable, writable, exceptional = select.select(inputs, outputs, inputs)
# Handle inputs
for s in readable:
if s is server:
# A "readable" server socket is ready to accept a connection
connection, client_address = s.accept()
print(‘new connection from‘, client_address)
connection.setblocking(False)
inputs.append(connection)
# Give the connection a queue for data we want to send
message_queues[connection] = Queue.Queue()
else:
data = s.recv(1024)
if data:
# A readable client socket has data
print(sys.stderr, ‘received "%s" from %s‘ % (data, s.getpeername()))
message_queues[s].put(data)
# Add output channel for response
if s not in outputs:
outputs.append(s)
else:
# Interpret empty result as closed connection
print(‘closing‘, client_address, ‘after reading no data‘)
# Stop listening for input on the connection
if s in outputs:
outputs.remove(s) # 既然客户端都断开了，我就不用再给它返回数据了，所以这时候如果这个客户端的连接对象还在outputs列表中，就把它删掉
inputs.remove(s) # inputs中也删除掉
s.close() # 把这个连接关闭掉
# Remove message queue
del message_queues[s]
# Handle outputs
for s in writable:
try:
next_msg = message_queues[s].get_nowait()
except Queue.Empty:
# No messages waiting so stop checking for writability.
print(‘output queue for‘, s.getpeername(), ‘is empty‘)
outputs.remove(s)
except KeyError:
continue
else:
print(‘sending "%s" to %s‘ % (next_msg, s.getpeername()))
s.send(next_msg)
# Handle "exceptional conditions"
for s in exceptional:
print(‘handling exceptional condition for‘, s.getpeername())
# Stop listening for input on the connection
inputs.remove(s)
if s in outputs:
outputs.remove(s)
s.close()
# Remove message queue
del message_queues[s]
socket 客户端：
#!/usr/bin/env python
# -*- coding:utf-8 -*-
__author__ = ‘admin‘
import socket
import sys
def select_sock(ip, port):
msg = u‘俺老孙来也!‘.encode(‘utf-8‘)
sock = [socket.socket(socket.AF_INET,socket.SOCK_STREAM),
socket.socket(socket.AF_INET,socket.SOCK_STREAM),
socket.socket(socket.AF_INET,socket.SOCK_STREAM),
socket.socket(socket.AF_INET,socket.SOCK_STREAM),
socket.socket(socket.AF_INET,socket.SOCK_STREAM),
socket.socket(socket.AF_INET,socket.SOCK_STREAM),
socket.socket(socket.AF_INET,socket.SOCK_STREAM),
]
for s in sock:
s.connect((ip, port))
s.send(msg)
print >> sys.stderr ,‘%s send :%s‘ % (s.getpeername(), msg)
for i in sock:
data = i.recv(1024)
print >> sys.stderr, ‘%s recv:%s ‘ % (i.getpeername(), data)
if not data:
print >> sys.stderr, ‘connect close!‘, i.getpeername()
if __name__ == ‘__main__‘:
server_addr = ‘192.168.1.111‘
server_port = 2288
select_sock(server_addr, server_port)