如果 Node.js 进程不是从 IPC 通道衍生出来的，则调用
If the Node.js process is spawned with an IPC channel (see the Child Process
and Cluster documentation), the
process.disconnect() method will close the
IPC channel to the parent process, allowing the child process to exit gracefully
once there are no other connections keeping it alive.
The effect of calling
process.disconnect() is the same as calling
ChildProcess.disconnect() from the parent process.
If the Node.js process was not spawned with an IPC channel,
process.disconnect() will be