How to close the client streams after they are disconnected? - multithreading

Question

there's a simple chat program using the asyncio library of Python. The clients can communicate without ever being blocked by any operation. Also the server prints out an information to the console window whenever a client is connected/disconnected to the server. Besides, all activity of the clients are written into a log file by the server.
There's no apparent problem when I look at the console windows. One second later after a client is disconnected, the information about that client is written to the console window of server. However when I look at the log file, it is seen that, the server is trying to send empty messages to all connected clients. But these messages are not displayed in clients' windows.
So it seems, the server is not properly closing the disconnected clients. The reader and writer streams of the disconnected client seems active even the client is disconnected.
How can this problem be solved according to the codes I've shared? By the way I am sharing the log file too. Here are the codes:
server.py
#!/usr/bin/env python3.7
# -*- coding: utf-8 -*-
import asyncio
import logging
logging.basicConfig(
filename="server.log",
format="- %(levelname)s - %(asctime)s - %(message)s",
level=logging.DEBUG,
datefmt="%d.%m.%Y %H:%M:%S"
)
class Server:
def __init__(self):
self.clients = []
def run(self):
asyncio.run(self.main())
async def client_connected(self, reader, writer):
client = f"{writer.get_extra_info('peername')}"
print(f"{client} is connected.")
logging.info(f"{client} is connected.")
self.clients.append((writer, reader))
while True:
try:
data = await reader.readline()
except (BrokenPipeError, ConnectionResetError):
data = "".encode()
await asyncio.sleep(1)
for i in self.clients:
msg = f"{client}: {data.decode()}"
try:
i[0].write(msg.encode())
logging.debug(msg[:-1])
await i[0].drain()
except (BrokenPipeError, ConnectionResetError):
i[0].close()
self.clients.remove(i)
print(f"{client} is disconnected.")
logging.info(f"{client} is disconnected.")
await asyncio.sleep(2)
break
async def main(self):
server = await asyncio.start_server(
client_connected_cb=self.client_connected,
host="127.0.0.1",
port=12345
)
print(f"Server started on {server.sockets[0].getsockname()}")
logging.info(f"Server started on {server.sockets[0].getsockname()}")
async with server:
await server.wait_closed()
if __name__ == "__main__":
Server().run()
client.py
#!/usr/bin/env python3.7
# -*- coding: utf-8 -*-
import sys
import asyncio
import threading
class Client:
def __init__(self):
self.nick = input("/nick ")
while not self.nick:
self.nick = input("/nick ")
def run(self):
asyncio.run(self.main())
async def read(self, reader, writer):
data = await reader.readline()
socket = writer.get_extra_info('socket').getsockname()
if str(socket) not in data.decode() or \
self.nick not in data.decode():
if data.decode().count("('") >= 1:
data = data.decode().split(": ")[-2:]
print(": ".join(data)[:-1])
async def write(self, writer):
t = threading.Thread(
target=lambda: writer.write(
f"{self.nick}: {sys.stdin.readline()}".encode()
)
)
t.daemon = True
t.start()
t.join(0.1)
await writer.drain()
async def main(self):
reader, writer = await asyncio.open_connection("127.0.0.1", 12345)
print(f"Connected to {writer.get_extra_info('peername')}")
while reader and writer:
await asyncio.gather(
self.read(reader, writer),
self.write(writer)
)
if __name__ == "__main__":
Client().run()
server.log
- DEBUG - 30.09.2019 15:17:50 - Using selector: EpollSelector
- INFO - 30.09.2019 15:17:50 - Server started on ('127.0.0.1', 12345)
- INFO - 30.09.2019 15:17:56 - ('127.0.0.1', 45562) is connected.
- INFO - 30.09.2019 15:18:05 - ('127.0.0.1', 45564) is connected.
- INFO - 30.09.2019 15:18:21 - ('127.0.0.1', 45566) is connected.
- DEBUG - 30.09.2019 15:18:48 - ('127.0.0.1', 45566): Client3: Hello Clients!
- DEBUG - 30.09.2019 15:18:48 - ('127.0.0.1', 45566): Client3: Hello Clients!
- DEBUG - 30.09.2019 15:18:48 - ('127.0.0.1', 45566): Client3: Hello Clients!
- DEBUG - 30.09.2019 15:18:51 - ('127.0.0.1', 45566): Client3: How are you?
- DEBUG - 30.09.2019 15:18:51 - ('127.0.0.1', 45566): Client3: How are you?
- DEBUG - 30.09.2019 15:18:51 - ('127.0.0.1', 45566): Client3: How are you?
- DEBUG - 30.09.2019 15:18:53 - ('127.0.0.1', 45566):
- DEBUG - 30.09.2019 15:18:53 - ('127.0.0.1', 45566):
- DEBUG - 30.09.2019 15:18:53 - ('127.0.0.1', 45566):
- DEBUG - 30.09.2019 15:18:53 - ('127.0.0.1', 45566):
- DEBUG - 30.09.2019 15:18:53 - ('127.0.0.1', 45566):
- DEBUG - 30.09.2019 15:18:53 - ('127.0.0.1', 45566):
- INFO - 30.09.2019 15:18:53 - ('127.0.0.1', 45566) is disconnected.
- DEBUG - 30.09.2019 15:18:55 - ('127.0.0.1', 45564):
- DEBUG - 30.09.2019 15:18:55 - ('127.0.0.1', 45564):
- DEBUG - 30.09.2019 15:18:55 - ('127.0.0.1', 45564):
- DEBUG - 30.09.2019 15:18:55 - ('127.0.0.1', 45564):
- INFO - 30.09.2019 15:18:55 - ('127.0.0.1', 45564) is disconnected.
- DEBUG - 30.09.2019 15:18:56 - ('127.0.0.1', 45566):
- DEBUG - 30.09.2019 15:18:57 - ('127.0.0.1', 45562):
- DEBUG - 30.09.2019 15:18:57 - ('127.0.0.1', 45562):
- INFO - 30.09.2019 15:18:57 - ('127.0.0.1', 45562) is disconnected.

Answer 1

According to the documentation of StreamWriter.close, it turns out you need to call wait_closed too:
stream.close()
await stream.wait_closed()
In your server code:
i[0].close()
await i[0].wait_closed()