What is the difference between Process and Thread in Python?

Question

Accepted Answer

**Process** has its own memory space and Python interpreter. **Thread** shares memory within a process.

```python
from multiprocessing import Process
import threading

# Process — separate memory
counter = 0

def process_worker():
    global counter
    counter += 100  # Each process has its own counter!

p1 = Process(target=process_worker)
p2 = Process(target=process_worker)
p1.start(); p2.start()
p1.join(); p2.join()
print(counter)  # 0 (unchanged!)

# Thread — shared memory
counter = 0
lock = threading.Lock()

def thread_worker():
    global counter
    with lock:
        counter += 100

t1 = threading.Thread(target=thread_worker)
t2 = threading.Thread(target=thread_worker)
t1.start(); t2.start()
t1.join(); t2.join()
print(counter)  # 200
```

**Comparison:**
- **Process**: own memory, bypasses GIL, slower IPC.
- **Thread**: shared memory, affected by GIL, faster IPC.
- **Process**: better for CPU-bound.
- **Thread**: better for I/O-bound.

Python: What is the difference between Process and Thread in Python?