[Python] Two threads using same socket object - Problem?

I found this example of a simple pyhton chat implementation in order to understand how sockets work.

#server
import socket, threading #Libraries import

host = '127.0.0.1' #LocalHost
port = 7976 #Choosing unreserved port

server = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #socket initialization
server.bind((host, port)) #binding host and port to socket
server.listen()

clients = []
nicknames = []

def broadcast(message): #broadcast function declaration
for client in clients:
client.send(message)

def handle(client):
while True:
try: #recieving valid messages from client
message = client.recv(1024)
broadcast(message)
except: #removing clients
index = clients.index(client)
clients.remove(client)
client.close()
nickname = nicknames[index]
broadcast('{} left!'.format(nickname).encode('ascii'))
nicknames.remove(nickname)
break

def receive(): #accepting multiple clients
while True:
client, address = server.accept()
print("Connected with {}".format(str(address)))
client.send('NICKNAME'.encode('ascii'))
nickname = client.recv(1024).decode('ascii')
nicknames.append(nickname)
clients.append(client)
print("Nickname is {}".format(nickname))
broadcast("{} joined!".format(nickname).encode('ascii'))
client.send('Connected to server!'.encode('ascii'))
thread = threading.Thread(target=handle, args=(client,))
thread.start()

receive()


#client
import socket, threading


nickname = input("Choose your nickname: ")

client = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #socket initialization
client.connect(('127.0.0.1', 7976)) #connecting client to server

def receive():
while True: #making valid connection
try:
message = client.recv(1024).decode('ascii')
if message == 'NICKNAME':
client.send(nickname.encode('ascii'))
else:
print(message)
except: #case on wrong ip/port details
print("An error occured!")
client.close()
break
def write():
while True: #message layout
message = '{}: {}'.format(nickname, input(''))
client.send(message.encode('ascii'))

receive_thread = threading.Thread(target=receive) #receiving multiple messages
receive_thread.start()
write_thread = threading.Thread(target=write) #sending messages
write_thread.start()


The client script uses two threads for writing and receiving data. Both threads use the same client socket. Is that a Problem?

My understanding by now is that client.recv() will block the socket (and it's own thread) and make the writing-thread fail - or wise versa. Is that right?

I saw this: can-two-threads-use-the-same-socket-at-the-same-time-and-are-there-possible-pro

It just states that it is possible to use two threads for receiving and writing as long as you coordinate well.

My question is: If client.recv() is using the socket to listen all the time, how can the other thread send data?

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