Concurrency

Concurrency lets your program do multiple things at once. Common models include threads, processes, and async I/O.

Threads vs Processes vs Async

• Threads share memory within a process; use locks to synchronize access.
• Processes have separate memory; communication uses IPC.
• Async uses an event loop and cooperative multitasking (async/await).

Race Conditions and Synchronization

Protect shared state with locks or use message-passing to avoid shared mutable state.

Example (Python sketch)

import threading

counter = 0
lock = threading.Lock()

def worker():
    global counter
    for _ in range(1000):
        with lock:
            counter += 1