What is the `multiprocessing` module?

Question

Accepted Answer

**multiprocessing** — parallel execution using separate processes.

```python
from multiprocessing import Process, Pool, Queue
import time

# Process-based parallelism
def cpu_bound(n):
    return sum(i * i for i in range(n))

# Pool for map operations
with Pool(4) as pool:
    results = pool.map(cpu_bound, [10**6] * 4)
    print(results)

# Manual process management
processes = []
for i in range(4):
    p = Process(target=cpu_bound, args=(10**6,))
    p.start()
    processes.append(p)

for p in processes:
    p.join()

# Queue for inter-process communication
q = Queue()

def producer(q):
    for i in range(5):
        q.put(i)
    q.put(None)  # Sentinel

def consumer(q):
    while (item := q.get()) is not None:
        print(f"Got: {item}")
```

**vs threading:**
- Multiprocessing bypasses GIL.
- Higher memory overhead.
- IPC via Queue, Pipe, shared memory.

Python: What is the `multiprocessing` module?