worker.send(message[, sendHandle[, options]][, callback])

• message <Object>
• sendHandle <Handle>
• options <Object> options 参数（如果存在）是用于参数化某些类型句柄的发送的对象。 options 支持以下属性：
  • keepOpen <boolean> 当传入 net.Socket 实例时可以使用的值。 当为 true 时，套接字在发送过程中保持打开状态。 默认值: false。
• callback <Function>
• 返回: <boolean>

向工作进程或主进程发送消息，可选择使用句柄。

在主进程中，这会向特定的工作进程发送消息。 它与 ChildProcess.send() 相同。

在工作进程中，这会向主进程发送消息。 它与 process.send() 相同。

此示例将回显来自主进程的所有消息：

if (cluster.isPrimary) {
  const worker = cluster.fork();
  worker.send('hi there');

} else if (cluster.isWorker) {
  process.on('message', (msg) => {
    process.send(msg);
  });
}

• message <Object>
• sendHandle <Handle>
• options <Object> The options argument, if present, is an object used to parameterize the sending of certain types of handles. options supports the following properties:
  • keepOpen <boolean> A value that can be used when passing instances of net.Socket. When true, the socket is kept open in the sending process. Default: false.
• callback <Function>
• Returns: <boolean>

Send a message to a worker or primary, optionally with a handle.

In the primary, this sends a message to a specific worker. It is identical to ChildProcess.send().

In a worker, this sends a message to the primary. It is identical to process.send().

This example will echo back all messages from the primary:

if (cluster.isPrimary) {
  const worker = cluster.fork();
  worker.send('hi there');

} else if (cluster.isWorker) {
  process.on('message', (msg) => {
    process.send(msg);
  });
}