Epoll+线程池工作原理

Epoll+线程池的工作原理如下：
1. 单线程创建epoll并等待，有I/O请求（socket）到达时，将其加入epoll并从线程池中取一个空闲工作者线程，将实际的业务交由工作者线程处理。
2. 当多个任务到来时，Epoll及时响应并将任务下发给特定的处理线程，完成对应的任务。
3. 如果只用单线程进行listen轮询监听的话，效率上实在是太低。而借助epoll的话就会很完美的解决这个问题。
4. 使用线程池的缘由是为了避免频繁创建和销毁线程，提高线程的复用率和效率。

代码示例：

import socket
import threading
import queue
import select

# 定义线程池类
class ThreadPool:
    def __init__(self, max_workers):
        self.max_workers = max_workers
        self._workers = []
        self._task_queue = queue.Queue()
        self._init_workers()

    # 初始化线程池
    def _init_workers(self):
        for i in range(self.max_workers):
            worker = threading.Thread(target=self._worker)
            worker.start()
            self._workers.append(worker)

    # 工作者线程
    def _worker(self):
        while True:
            try:
                func, args, kwargs = self._task_queue.get()
                func(*args, **kwargs)
            except Exception as e:
                print(e)

    # 提交任务
    def submit(self, func, *args, **kwargs):
        self._task_queue.put((func, args, kwargs))

# 定义服务端类
class Server:
    def __init__(self, host, port, max_workers):
        self.host = host
        self.port = port
        self.max_workers = max_workers
        self.server_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        self.server_socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
        self.server_socket.bind((self.host, self.port))
        self.server_socket.listen(5)
        self.thread_pool = ThreadPool(self.max_workers)

    # 处理客户端请求
    def handle_request(self, client_socket, client_address):
        print(f"Connected by {client_address}")
        while True:
            data = client_socket.recv(1024)
            if not data:
                break
            client_socket.sendall(data)
        client_socket.close()

    # 运行服务端
    def serve_forever(self):
        print(f"Server is running on {self.host}:{self.port}")
        while True:
            client_socket, client_address = self.server_socket.accept()
            self.thread_pool.submit(self.handle_request, client_socket, client_address)

# 运行服务端
if __name__ == '__main__':
    server = Server('localhost', 8888, 10)
    server.serve_forever()