process.channel.ref()
如果之前已调用过 .unref(),则此方法使 IPC 通道保持进程的事件循环运行。
¥This method makes the IPC channel keep the event loop of the process
running if .unref() has been called before.
通常,这是通过 process 对象上的 'disconnect' 和 'message' 监听器的数量来管理的。但是,此方法可用于显式请求特定行为。
¥Typically, this is managed through the number of 'disconnect' and 'message'
listeners on the process object. However, this method can be used to
explicitly request a specific behavior.