python 主进程执行系统命令重启后，子进程占用端口解决

因业务需要，需监听tcp端口

def tcpListener():
    #建立tcp头
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, True)
    sock.bind(('0.0.0.0', 8888))
    #最大连接数
    sock.listen(5)
    
    while True:
        try:
            #获取连接
            session, addr = sock.accept()
            conn = Server();
            t = threading.Thread(target=conn.connect, args=(session, addr))
            t.daemon = True
            t.start()
        except Exception, e:
            logger.error(traceback.format_exc())

将该监听嵌入到主进程server.py当中

#监听tcp端口
t = MyThread(target=tcpListener)
t.setDaemon(True)
t.start()

#do something...

当中有业务需要执行shell脚本重启主进程

subprocess.Popen((u'nohup sh restart.sh', shell=True
         , stdout=subprocess.PIPE, stderr=subprocess.PIPE)

启动时发现错误，端口被占用

Traceback (most recent call last):
  File "/usr/lib64/python2.7/multiprocessing/process.py", line 258, in _bootstrap
    self.run()
  File "/usr/lib64/python2.7/multiprocessing/process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "/mnt/hgfs/workspace/octopus/jtools/server.py", line 18, in ssh_server_main
    sock.bind(('0.0.0.0', int(port)))
  File "/usr/lib64/python2.7/socket.py", line 224, in meth
    return getattr(self._sock,name)(*args)
error: [Errno 98] Address already in use

netstat -nultp查看端口发现，端口绑定到了一些奇怪的服务上面。经资料查询，开启子进程的时候，子进程会继承父进程的文件描述符。加入close_fds=True参数，让子进程不继承文件描述符即可解决

subprocess.Popen((u'nohup sh restart.sh', shell=True
         , stdout=subprocess.PIPE, stderr=subprocess.PIPE, close_fds=True)

 参考资料：Python subprocess.Popen() - subprocess causes sockets to remain open - Stack Overflow