.is_alive()、setdeamon()の使い方

chatclient.pyで常に受信待ちをしてchatserver.pyからデータ送信があるたびに反応するプログラムに使われている.is_aliveとsetDeamonを使い方、機能を教えて欲しいです。

プログラム

chatserver.py

python
1# -*- coding: <encoding name> -*-
2
3import socket
4
5port = 50000
6bufsize = 4096
7
8server = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
9server.bind(("", port))
10clist = []
11
12while True:
13    data, client = server.recvfrom(bufsize)
14    if not (client in clist):
15        clist.append(client)
16    if data.decode("utf-8") == 'q':
17        clist.remove(client)
18    else:
19        msg = str(client) + ">"
20        msg += data.decode("utf-8")
21        print(msg)
22        for c in clist:
23            server.sendto(msg.encode("utf-8"), c)
24

chatclient.py

python
1# -*- coding: <encoding name> -*-
2
3import socket
4import threading
5import sys
6
7port = 50000
8bufsize = 4096
9
10def server_handler(client):
11    while True:
12        try:
13            data = client.recv(bufsize)
14            print(data.decode("utf-8"))
15        except:
16            sys.exit()
17    client.close()
18
19client = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
20host = input("接続先サーバ：")
21if host == "":
22    host = "localhost"
23p = threading.Thread(target=server_handler, args=(client,))
24p.setDaemon(True)
25
26while True:
27    msg = input("")
28    client.sendto(msg.encode("utf-8"), (host, port))
29    if msg == "q":
30        break
31    if not p.is_alive():
32        p.start()
33    
34
35client.close()
36