OK,首先写一个pythone socket的server段,对开放三个端口:10000,10001,10002.krondo的例子中是每个server绑定一个端口,测试的时候需要分别开3个shell,分别运行.这太麻烦了,就分别用三个Thread来运行这些services.

import optparse
import os
import socket
import time
from threading import Thread
import StringIO
 
txt = '''1111
2222
3333
4444
'''
 
def server(listen_socket):
 while True:
 buf = StringIO.StringIO(txt)
 sock, addr = listen_socket.accept()
 print 'Somebody at %s wants poetry!' % (addr,)
 while True:
 try:
 line = buf.readline().strip()
 if not line:
 sock.close()
 break
 sock.sendall(line) # this is a blocking call
 print 'send bytes to client:%s' % line
 #sock.close()
 except socket.error:
 sock.close()
 break
 time.sleep(1) #server和client连接后，server会故意每发送一个单词后等待一秒钟后再发送另一个单词
 
 
def main():
 ports = [10000, 10001, 10002]
 for port in ports:
 listen_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 listen_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
 addres = (str('127.0.0.1'), port)
 listen_socket.bind(addres)
 listen_socket.listen(5)
 print "start listen at:%s" % (port,)
 worker = Thread(target = server, args = [listen_socket])
 worker.setDaemon(True)
 worker.start()
 
 
if __name__ == '__main__':
 main()
 while True:
 time.sleep(0.1) #如果不sleep的话,CPU会被Python完全占用了
 pass

下面是一个client,没有才用异步网络,连接这个三个端口的server:

import socket
 
 
if __name__ == '__main__':
 ports = [10000, 10001, 10002]
 for port in ports:
 address = (str('127.0.0.1'), port)
 sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 sock.connect(address)
 poem = ''
 while True:
 data = sock.recv(4)
 if not data:
 sock.close()
 break
 poem += data
 print poem

下面用异步的client来读取，代码如下：

import datetime, errno, optparse, select, socket
 
def connect(port):
 """Connect to the given server and return a non-blocking socket."""
 address = (str('127.0.0.1'), port)
 sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
 sock.connect(address)
 sock.setblocking(0)
 return sock
 
def format_address(address):
 host, port = address
 return '%s:%s' % (host or '127.0.0.1', port)
 
if __name__ == '__main__':
 ports = [10000, 10001, 10002]
 start = datetime.datetime.now()
 
 sockets = map(connect, ports)
 poems = dict.fromkeys(sockets, '') # socket -> accumulated poem 
 
 # socket -> task numbers
 sock2task = dict([(s, i + 1) for i, s in enumerate(sockets)])
 sockets = list(sockets) # make a copy
 
 while sockets:
 #运用select来确保那些可读取的异步socket可以立即开始读取IO
 #OS不停的搜索目前可以read的socket，有的话就返回rlist
 rlist, _, _ = select.select(sockets, [], [])
 for sock in rlist:
 data = ''
 while True:
 try:
 new_data = sock.recv(1024)
 except socket.error, e:
 if e.args[0] == errno.EWOULDBLOCK:
 break
 raise
 else:
 if not new_data:
 break
 else:
 print new_data
 data += new_data
 
 task_num = sock2task[sock]
 if not data:
 sockets.remove(sock)
 sock.close()
 print 'Task %d finished' % task_num
 else:
 addr_fmt = format_address(sock.getpeername())
 msg = 'Task %d: got %d bytes of poetry from %s'
 print msg % (task_num, len(data), addr_fmt)
 
 poems[sock] += data
 
 elapsed = datetime.datetime.now() - start
 print 'Got poems in %s' % elapsed

结果只需要4秒就完成了读取任务。效率是刚才同步socket的三倍。对客户端的异步改造主要有两点：

同步模式下，客户端分别创建socket；而在异步模式下，client开始就创建了所有的socket。

通过“sock.setblocking(0)”设置socket为异步模式。

通过Unix系统的select俩返回可读取IO

最为核心的是26行和29行。尤其是29行的select操作返回待读取socket的列表。