socket Module Complexity¶

The socket module provides low-level network communication interfaces for client and server applications.

Complexity Reference¶

Operation	Time	Space	Notes
`socket()`	O(1)	O(1)	Create socket
`connect()`	O(1) + network latency	O(1)	Network latency and handshake dominate
`send()`	O(k)	O(1)	k = data size
`recv()`	O(k)	O(k)	k = buffer size

Basic Client¶

import socket

# Create socket - O(1)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# Connect to server - O(n)
sock.connect(('localhost', 8000))  # O(n) - network time

# Send data - O(k)
sock.send(b'Hello')  # O(5)

# Receive data - O(k)
data = sock.recv(1024)  # O(k) - up to 1024 bytes

# Close - O(1)
sock.close()

Basic Server¶

import socket

# Create socket - O(1)
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

# Bind to port - O(1)
sock.bind(('localhost', 8000))  # O(1)

# Listen for connections - O(1)
sock.listen(1)  # O(1)

# Accept connection - O(n)
client, addr = sock.accept()  # O(n) - wait for client

# Communicate - O(k)
data = client.recv(1024)  # O(k)
client.send(b'Response')  # O(8)

# Close - O(1)
client.close()
sock.close()

Server Loop¶

import socket

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.bind(('localhost', 8000))
sock.listen(5)

# Accept multiple clients - O(n) per client
while True:
    client, addr = sock.accept()  # O(n) - wait

    # Handle client - O(k)
    try:
        while True:
            data = client.recv(1024)  # O(k)
            if not data:
                break
            response = process(data)  # O(f)
            client.send(response)  # O(len(response))
    finally:
        client.close()  # O(1)

UDP (Connectionless)¶

import socket

# UDP socket - O(1)
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)

# Bind - O(1)
sock.bind(('localhost', 8000))

# Receive from - O(k)
data, addr = sock.recvfrom(1024)  # O(k)

# Send to - O(k)
sock.sendto(b'Response', addr)  # O(k)

Version Notes¶

Python 2.x: socket available
Python 3.x: Same with IPv6 improvements
Note: Network I/O dominates - algorithms are secondary

Best Practices¶

✅ Do:

Use context managers (with statement)
Set timeouts
Close sockets properly
Use asyncio for many connections

❌ Avoid:

Blocking operations in GUI
No timeout (hangs)
Not closing sockets
Synchronous servers for many clients