What is multiprocessing.Queue and how does it differ from queue.Queue?

Question

Accepted Answer

**multiprocessing.Queue** works across **processes**. **queue.Queue** works within a **single thread/process**.

```python
# multiprocessing.Queue — inter-process communication
from multiprocessing import Process, Queue

def producer(q):
    for i in range(5):
        q.put(i ** 2)
    q.put(None)  # Sentinel

def consumer(q):
    while True:
        item = q.get()  # Blocks until item available
        if item is None:
            break
        print(f"Got: {item}")

q = Queue()
p1 = Process(target=producer, args=(q,))
p2 = Process(target=consumer, args=(q,))
p1.start()
p2.start()
p1.join()
p2.join()

# queue.Queue — thread-safe within one process
import queue

q = queue.Queue()
q.put("item")  # Thread-safe put
item = q.get()  # Thread-safe get
```

**Key differences:**
- **multiprocessing.Queue**: pickle-based, IPC, slower.
- **queue.Queue**: in-memory, thread-safe, faster.
- Use `multiprocessing.Queue` for process communication.
- Use `queue.Queue` for thread communication.

Python: What is multiprocessing.Queue and how does it differ from queue.Queue?