事件：'listening'

🌐 Event: 'listening'

• worker <cluster.Worker>
• address <Object>

在工作线程中调用 listen() 后，当服务器发出 'listening' 事件时，主进程中的 cluster 也会发出 'listening' 事件。

🌐 After calling listen() from a worker, when the 'listening' event is emitted on the server, a 'listening' event will also be emitted on cluster in the primary.

事件处理程序会使用两个参数执行，其中 worker 包含 worker 对象，address 对象包含以下连接属性：address、port 和 addressType。如果 worker 在多个地址上监听，这非常有用。

🌐 The event handler is executed with two arguments, the worker contains the worker object and the address object contains the following connection properties: address, port, and addressType. This is very useful if the worker is listening on more than one address.

cluster.on('listening', (worker, address) => {
  console.log(
    `A worker is now connected to ${address.address}:${address.port}`);
}); 拷贝

addressType 可以是以下之一：

🌐 The addressType is one of:

• 4（TCPv4）
• 6（TCPv6）
• -1（Unix 域套接字）
• 'udp4' 或 'udp6'（UDPv4 或 UDPv6）