node.js - node async queue中这个callback是什么，为什么这里输出只有5行？

Question

Answer 1

当然咯，因为你并发量是5，但是你的queue中并没有fork callback，所以并发量是5，没有结束也不会调新的咯。

var async = require('async');
var q = async.queue(function(data, callback) {
  console.log(data.name);
// fork callback
  callback();
}, 5);
for(var i = 0; i < 10; ++i) {
  q.push({ name: 0 })
}

Answer 2

var q = async.queue(function (data, callback) {
    console.log(data.name);
    callback(null)
},5)

少了callback

An asynchronous function for processing a queued task, which must call its callback(err) argument when finished, with an optional error as an argument. If you want to handle errors from an inpidual task, pass a callback to q.push(). Invoked with (task, callback).