Python select sets the timeout. After a while, it does not return.

I am writing a web server. Centos, interacts with multiple clients and uses the select model. After running for a period of time, the program suddenly gets stuck in select. It is clear that socket is in establish status, and there should be packets on it, but select does not return. Not sure if there is something wrong with the select mechanism or something else. Code:

ip="x.x.x.x"
port1 = 8322
server = socket.socket()
server.setblocking(False)
server.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
server.bind((ip,port1));
server.listen(10)
cli_socket = socket.socket()
cli_socket.setblocking(False)
host = "127.0.0.1"
port2 = 12355
cli_socket.setsockopt(socket.SOL_SOCKET,socket.SO_REUSEADDR,1)
cli_socket.bind((host, port2))
cli_socket.listen(5)
inputs=[server,cli_socket,]
while True:
readable, writable, exceptional = select.select(inputs, outputs, inputs, 30)
for s in readable:
    if s is server:
        conn,address = server.accept()
        rec_buf=conn.recv(1024)
        //make some handle here, store this connection in global data
        conn.setblocking(0)
        conn.sendall("pass")
        inputs.append(conn)
    elif s is cli_socket:
        cli_conn, addr = s.accept()
        command = cli_conn.recv(1024)
        ret=command.split(",")
            if ret[0] == "OPEN":                                                
                total_key[ret[1]].conn_sock.sendall("open")
                cli_conn.send("success")
                cli_conn.close()
    else:
        rec_buf=s.recv(1024)                                        
        //make some handle here                        
        s.sendall("ok")
for s in exceptional:
    inputs.remove(s)
    s.close()

1 conn,address = server.accept() 2 rec_buf=conn.recv(1024) 3 //make some handle here, store this connection in global data 4 conn.setblocking(0) 5 conn.sendall("pass")

-sharp -*- coding: utf-8 -*- import asyncio async def handle_server(reader, writer): data = await reader.readexactly(10) print('recv1: {}'.format(data.decode())) writer.write('pass'.encode()) writer.close() async def handle_client(reader, writer): data = await reader.readexactly(4) if data.decode() == 'OPEN': writer.write('success'.encode()) writer.close() def new_listener(loop, ip, port, handler): coro = asyncio.start_server(handler, ip, port, loop=loop) return loop.run_until_complete(coro) if __name__ == "__main__": loop = asyncio.get_event_loop() new_listener(loop, '127.0.0.1', 8322, handle_server), new_listener(loop, '127.0.0.1', 12355, handle_client), loop.run_forever()