TCP死锁演示

最新推荐文章于 2024-06-08 11:01:07 发布

转载最新推荐文章于 2024-06-08 11:01:07 发布 · 633 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/alben-cisco/p/7075508.html

文章标签：

#网络 #python

本文通过一个简单的Python脚本示例介绍了TCP死锁的概念及其实现。两个程序共享资源时，若因计划不当导致其中一个程序必须等待另一个程序释放资源才能继续运行，则形成死锁。文章提供了客户端与服务器端的代码实现。

TCP死锁：

两个程序共享有限的资源，由于糟糕的计划，A程序只能等待B程序资源占用结束后才能使用资源，这种情况就是死锁（deadlock）

代码的解释明天给出

#!/usr/bin/env python3
#-*- encoding:utf8 -*-

import argparse,sys,socket

def server(host,port,bytecount):
    sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    sock.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
    sock.bind((host,port))
    sock.listen(5)
    print("listening at",sock.getsockname())

    while True:
        sc,addr = sock.accept()
        print("Processing up to 1024 Bytes at a time from",addr)

        n = 0
        while True:
            data = sc.recv(1024)
            if not data:break
            output = data.decode().upper().encode()
            sc.sendall(output)
            n += len(data)
            print("\r %d Bytes process so far" %(n,),end='')
            sys.stdout.flush()
        sc.close()
        print("socket closed")

def client(host,port,bytecount):
    sock = socket.socket(socket.AF_INET,socket.SOCK_STREAM)
    bytecount = (bytecount+15) // 16 * 16
    message = ("capitalize this!").encode()

    print("sending",bytecount,"bytes of data , in chunks of 16 bytes")
    sock.connect((host,port))

    sent = 0
    while sent < bytecount:
        sock.sendall(message)
        sent+= len(message)
        print("\r %d Bytes sent" %(sent,),end='')
        sys.stdout.flush()
    print()
    sock.shutdown(socket.SHUT_WR)

    print('receiving all the data the server sends back')

    received = 0

    while True:
        data = sock.recv(42)
        if not received:print('The first data received says',repr(data))
        if not data:break
        received += len(data)
        print('\r %d Bytes received' %(received,),end='')
    print()
    sock.close()


if __name__ == "__main__":
    choices = {
        "client":client,
        "server":server
    }
    parser = argparse.ArgumentParser(description='Get deadlocked over TCP')
    parser.add_argument('role',choices=choices,help='which role to play')
    parser.add_argument('host',help='interface the server listen it;''host the client to send')
    parser.add_argument('bytecount', type = int , nargs = "?" , default=16 , help='number of bytes for cleint to send (default 16)')
    parser.add_argument('-p', metavar='PORT' ,type=int , default=1060 , help='TCP PORT(default 1060)')

    args = parser.parse_args()
    function=choices[args.role]
    function(args.host, args.p , args.bytecount)