【node.js】一度に実行する非同期処理の数を制限して、何回かに分けて処理する

Essential Node.js patterns and snippets

exports.Pile = function() {
   this.pile = [];
   this.concurrency = 0;
   this.done = null;
   this.max_concurrency = 10;
}
exports.Pile.prototype = {
  add: function(callback) {
   this.pile.push(callback);
  },
  run: function(done, max_concurrency) {
      this.done = done || this.done;
      this.max_concurrency = max_concurrency || this.max_concurrency;
      var target = this.pile.length;
      var that = this;
      var next = function() {
         that.concurrency--;
         (--target == 0 ? that.done() : that.run());
      };
      while(this.concurrency < this.max_concurrency && this.pile.length > 0) {
         this.concurrency++;
         var callback = this.pile.shift();
         callback(next);
      }
   }
};

exports.Pile = function() {

this.pile = [];

this.concurrency = 0;

this.done = null;

this.max_concurrency = 10;

}

exports.Pile.prototype = {

add: function(callback) {

this.pile.push(callback);

run: function(done, max_concurrency) {

this.done = done || this.done;

this.max_concurrency = max_concurrency || this.max_concurrency;

var target = this.pile.length;

var that = this;

var next = function() {

that.concurrency--;

(--target == 0 ? that.done() : that.run());

};

while(this.concurrency < this.max_concurrency && this.pile.length > 0) {

this.concurrency++;

var callback = this.pile.shift();

callback(next);

}

};

使用例）

var pile = require("./pile.js").Pile;
var pilex = new pile();

var counter = 0;
 
for(var i = 0; i < 50; i++) {
   pilex.add( function test(next) {　　//実行する非同期処理を登録
      setTimeout( function() {
         counter++;
         console.log(counter +" Hello world");
         next();
      }, 1500);
     }
   );
}
pilex.run(function() {  //登録した処理を実行
	console.log("Done "+counter);
	}, 5); //一度に実行する非同期処理の制限数

var pile = require("./pile.js").Pile;

var pilex = new pile();

var counter = 0;

for(var i = 0; i < 50; i++) {

pilex.add( function test(next) {　　//実行する非同期処理を登録

setTimeout( function() {

counter++;

console.log(counter +" Hello world");

next();

}, 1500);

}

);

}

pilex.run(function() { //登録した処理を実行

console.log("Done "+counter);

}, 5); //一度に実行する非同期処理の制限数

サンプル

投稿者: shimizu