怎样用Python创建线程池？

from concurrent.futures import ThreadPoolExecutor, as_completed

def my_task(n):
    return n * n

with ThreadPoolExecutor(max_workers=5) as executor:
    futures = [executor.submit(my_task, i) for i in range(10)]
    for future in as_completed(futures):
        result = future.result()
        print(f"Result: {result}")

from concurrent.futures import ThreadPoolExecutor

def task_with_exception(n):
    if n == 5:
        raise ValueError("Something went wrong")
    return n * n

with ThreadPoolExecutor(max_workers=5) as executor:
    futures = [executor.submit(task_with_exception, i) for i in range(10)]
    for future in futures:
        try:
            result = future.result()
            print(f"Result: {result}")
        except Exception as e:
            print(f"An error occurred: {e}")

from concurrent.futures import ThreadPoolExecutor
from threading import Semaphore

def task_with_semaphore(n, semaphore):
    with semaphore:
        return n * n

semaphore = Semaphore(3)  # 同一时间最多运行3个任务

with ThreadPoolExecutor(max_workers=5) as executor:
    futures = [executor.submit(task_with_semaphore, i, semaphore) for i in range(10)]
    for future in futures:
        result = future.result()
        print(f"Result: {result}")

from concurrent.futures import ProcessPoolExecutor

def cpu_bound_task(n):
    return sum(i * i for i in range(n))

with ProcessPoolExecutor(max_workers=4) as executor:
    futures = [executor.submit(cpu_bound_task, 1000000) for _ in range(4)]
    for future in futures:
        result = future.result()
        print(f"Result: {result}")