如何在node.js子进程模块中将消息以及stdout从子进程传递给父进程？

Question

我遇到了child-process模块​​的问题，特别是child.spawn和child.fork。 我靠child_process.fork的文档，它说的：

This is a special case of the child_process.spawn() functionality for spawning Node.js processes. In addition to having all the methods in a normal ChildProcess instance, the returned object has a communication channel built-in. See child.send(message, [sendHandle]) for details.

我已经简化下面我的问题：

parent.js是：

var cp = require('child_process'); 
var n = cp.fork('./child.js'); 
n.send({a:1}); 
//n.stdout.on('data',function (data) {console.log(data);}); 
n.on('message', function(m) { 
    console.log("Received object in parent:"); 
    console.log(m); 
}); 

child.js是：

process.on('message', function(myObj) { 
    console.log('myObj received in child:'); 
    console.log(myObj); 
    myObj.a="Changed value"; 
    process.send(myObj); 
}); 
process.stdout.write("Msg from child"); 

正如所料。输出是：

Msg from child 
myObj received in child: 
{ a: 1 } 
Received object in parent: 
{ a: 'Changed value' } 

我希望它与parent.js中的注释行一起使用uncommented。换句话说，我要赶在子进程标准输出的n.stdout.on（“数据” ......父进程声明如果我取消它，我得到一个错误：

n.stdout.on('data',function (data) {console.log(data);}); 
    ^
TypeError: Cannot read property 'on' of null 

我不介意使用任何子进程异步变体，exec，fork或spawn。任何建议？

Answer 1

当您按顺序将它传递给fork（）时，需要在options对象上设置silent属性为stdin，stdout和stderr返回父进程。

例如var n = cp.fork('./child.js', [], { silent: true });