Question

我正在尝试从主进程中的子进程中捕获一些响应。我可以在主进程中记录子进程的信息但无法捕获一些返回xyz响应。这是主进程的代码：

var express  = require('express');
var app = express();
const
             fs = require('fs'),
             cp = require('child_process');
 app.get('/',onRequest );
    function onRequest(request, response) {
                var express  = require('express');
             var app = express();

            var child= cp.spawn('node' ,['./child_process/block.js'],filestreamCallback);
            child.stdout.on('data', function(data) {
                console.log('stdout: ==== ' + data);
            });
            child.stderr.on('data', function(data) {
                console.log('stdout: ' + data);
            });
            child.on('close', function(code) {
                console.log('closing code: ' + code);
            });
        function filestreamCallback() {
                response.writeHead(200, {'Content-Type': 'text/plain'});
                baflog.info("Reading Stream completed");
                response.write('Thanks for Your patience!\n');
                response.end();
            }
        }
        app.listen(5000);
        console.log('Server started');

Child process : block.js

        /*Keep waiting for 10 seconds*/

    console.log("Waiting for child Process (block.js) to complete......");
    var startTime = new Date().getTime();
    while (new Date().getTime() < startTime + 10000);
    ret_resp();
    var response = {status:'success'};
    function ret_resp(){
        return response;
    }
    console.log("Thank You for waiting......");

在控制台中我看到输出为： stdout ====：等待子进程（block.js）完成...... -punws-sohan

stdout：====感谢您的等待......

我看不到返回响应语句的输出任何人都可以建议如何捕捉儿童过程的反应吗？

Answer 1

首先，busy循环占用了不必要的CPU时间。只需使用setTimeout()即可。例如：

setTimeout(function() {
  ret_resp();
  // ...
}, 10000);

其次，您不能指望return将返回的值神奇地写入父进程。试试这个：

// parent.js
var child = cp.fork('./child_process/block.js', [], { silent: true });
child.stdout.on('data', function(data) {
  console.log('stdout: ==== ' + data);
});
child.stderr.on('data', function(data) {
  console.log('stdout: ' + data);
});
child.on('message', function(msg) {
  console.log('message from child: ' + require('util').inspect(msg));
});
child.on('close', function(code) {
  console.log('closing code: ' + code);
});


// child.js
console.log('Waiting for child Process (block.js) to complete......');
setTimeout(function() {
  var response = {status:'success'};
  function ret_resp() {
    process.send(response);
  }
  ret_resp();
  console.log('Thank You for waiting......');
}, 10000);

如何从nodejs中捕获子进程的响应

1 个答案: