pickle problem

[Gribouillis]

you end up with 2... objects in the same pickle file.

Here is an example of this feature with sockets: A client connects to a server and sends three Python objects by successive calls to pickle.dump() in the same file-like object. The server receives the Python objects and prints them.

Server code:

# pickserver.py
import pickle
import socket
import sys

# Create a TCP/IP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

# Bind the socket to the port
server_address = ('localhost', 10000)
print('starting up on {} port {}'.format(*server_address))
sock.bind(server_address)

# Listen for incoming connections
sock.listen(1)

while True:
    # Wait for a connection
    print('waiting for a connection')
    connection, client_address = sock.accept()
    try:
        print('connection from', client_address)
        connection.shutdown(socket.SHUT_WR)
        file = connection.makefile(mode='rb')
        unpic = pickle.Unpickler(file)
        # Receive Python objects and print them
        while True:
            try:
                obj = unpic.load()
            except EOFError:
                break
            else:
                print(f'received: {repr(obj)}')
    finally:
        # Clean up the connection
        connection.close()

Client code:

# pickclient.py
import pickle
import socket
import sys

# Create a TCP/IP socket
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# Connect the socket to the port where the server is listening
server_address = ('localhost', 10000)
print('connecting to {} port {}'.format(*server_address))
sock.connect(server_address)
sock.shutdown(socket.SHUT_RD)
file = sock.makefile(mode='wb')
pick = pickle.Pickler(file)

try:
    # Send Python objects
    data = [
        10,
        [2, 'spam', 'eggs'],
        (5, 7, 11),
    ]
    for obj in data:
        print(f'sending: {repr(obj)}')
        pick.dump(obj)

finally:
    print('closing socket')
    sock.close()

Output on the server side:

Output:
λ python paillasse/pf/pickserver.py
starting up on localhost port 10000
waiting for a connection
connection from ('127.0.0.1', 34014)
received: 10
received: [2, 'spam', 'eggs']
received: (5, 7, 11)
waiting for a connection

Output on the client side

Output:
λ python paillasse/pf/pickclient.py
connecting to localhost port 10000
sending: 10
sending: [2, 'spam', 'eggs']
sending: (5, 7, 11)
closing socket