Bytes get concatenated while trying to send data over sockets

I was trying to send some data over sockets, but I noticed that the bytes I send sometimes just get concatenated together.

Sorry if the wording is not great, but here’s some example code to reproduce this problem:

# SERVER CODE

import socket, pickle
from _thread import start_new_thread

IP = "0.0.0.0"  # Address to bind to
PORT = 5555  # Arbitrary non-privileged port
DEFAULT_BYTES = 2048
total_connections_so_far = 0


def send(data, conn, pickle_data=True):
    try:
        if pickle_data:
            data = pickle.dumps(data)
        conn.sendall(data)
    except Exception as e:
        print("ERROR TRYING TO SEND DATA: ", e)


def threaded_client(conn, addr, user_id):

    send(b"Hello there!", conn, False)
    send(b"2nd message", conn, False)
    send(b"Last message", conn, False)

    conn.close()


with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
    # bind the socket to the host address and port
    s.bind((IP, PORT))
    print("Server started at: ", s.getsockname())

    # listen for connections
    s.listen()
    print("Server has started. waiting for connections...")

    while True:

        conn, addr = s.accept()
        print("[CONNECTED]: ", addr)
        total_connections_so_far += 1  # increment the totoal connections

        # start a thread for the new client
        start_new_thread(threaded_client, (conn, addr, total_connections_so_far))

☝🏻 server.py

# CLIENT CODE

import socket, pickle


class Network:
    def __init__(self):
        self.client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.server = ""
        self.port = 5555
        self.addr = (
            self.server,
            self.port,
        )

    # function to connect to the server
    def connect(self):
        try:
            self.client.connect(self.addr)
            print("Connected!")

        except Exception as e:
            print("error while trying to connect:", e)
            return False

    # send some data to the server
    def send(self, data, pickle_data=True):
        try:
            if pickle_data:
                data = pickle.dumps(data)

            self.client.sendall(data)

        except Exception as e:
            print("error while trying to send data:", e)
            return False

    # recieve some data from the server
    def recv(self, buffer_size=2048):
        try:
            data = self.client.recv(buffer_size)
            return data
        except Exception as e:
            print("error while recieving:", e)


client = Network()
client.connect()
data = client.recv()
print(data)

☝🏻 client.py

Try running the client code a few times and you’ll notice that sometimes, the data received is a concatenation of all 3 messages sent from the server.

So to get around this problem, I have been using time.sleep(1) after every time I send something, but this is obviously not a great idea.

I understand that this happens cuz ( correct me if I’m wrong ) I’m only sending tiny bits of data from the server, and expecting to receive 2048 bits on the client side, so the client waits for a while to try and receive the full amount of data.

But this is a pretty common problem and there must be a neat solution to it right?

I know I’m a total noob, but please help me!