Input block the subscriber/client of receiving message in Pub/Sub system - python-3.x

Question

I am trying to build a publisher/subscriber system. In simple words, a publisher can publish messages to all subscribers via a broker. Subscribers can support 2 functionalities: 1) receive a message from the broker 2) send a message to the broker with input method. But there is a problem: Subscribers block while waiting the input from stdin and they receive the publishers messages after input, even though no input is needed.
Ι wοuld like to solve the problem in this direction: while waiting for input from stdin, a subscriber can receive a message from publish. I tried "curses" but i failed.
I post a part of my code
subscriber.py
while True:
try:
command = input("Enter a command: ")
#command = sys.stdin.readline()
if command == "quit":
break
command.strip()
command_to_broker = process_command(command, sub_id)
if command_to_broker == error_message:
print("Command with wrong format!")
continue
sock.sendall(bytes(command_to_broker, ENCODING))
received = str(sock.recv(BUFFER_SIZE), ENCODING)
print("Received from BROKER: " + received)
except:
print("Error/Disconnect")
broker.py (starts a publisher thread)
def publisher_thread(connection, topics_and_subscribers, subscribers_and_ports, subscribers):
while True:
data = connection.recv(BUFFER_SIZE)
print("Command from PUBLISHER {}".format(data.decode(ENCODING)))
response = 'OK'
command = data.decode(ENCODING).split(" ", 3)
pub_id = command[0]
topic = command[2]
message = command[3]
if topic in topics_and_subscribers:
for s in subscribers:
print(s.getpeername())
sum = s.send(bytes(message, ENCODING))
print(sum)
if not data:
break
connection.sendall(bytes(response, ENCODING))
connection.close()