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Python异步Socket编程
异步网络据说能极大的提高网络server的连接速度,所以打算写一个专题,来学习和了解异步网络.因为Python有个非常出名的异步Lib:Twisted,所以就用Python来完成.
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.
Java代码
- 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:
Java代码
- 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:
Java代码
- 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。
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