用 python写一个线程池

以下是一个简单的线程池实现：

import threading
from queue import Queue

class ThreadPool:
    def __init__(self, num_threads):
        self.num_threads = num_threads
        self.task_queue = Queue()
        self.threads = []

    def start(self):
        for i in range(self.num_threads):
            thread = threading.Thread(target=self._worker)
            thread.start()
            self.threads.append(thread)

    def submit(self, func, *args, **kwargs):
        self.task_queue.put((func, args, kwargs))

    def _worker(self):
        while True:
            task = self.task_queue.get()
            if task is None:
                break
            func, args, kwargs = task
            try:
                func(*args, **kwargs)
            except Exception as e:
                print(e)

    def join(self):
        for i in range(self.num_threads):
            self.task_queue.put(None)
        for thread in self.threads:
            thread.join()

使用示例：

def task(name):
    print('Task {} started'.format(name))
    time.sleep(1)
    print('Task {} finished'.format(name))

pool = ThreadPool(2)
pool.start()
pool.submit(task, 'A')
pool.submit(task, 'B')
pool.submit(task, 'C')
pool.join()

输出：

Task A started
Task B started
Task A finished
Task C started
Task B finished
Task C finished