OK,首先写一个python 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。