node.jsにバックグラウンドシングルスレッドFIFOジョブキューを作成するには

Question

私はJS /ノードの初心者です.Javascriptの "並行性"のテーマの周りに頭を浮かべています。私は今までにコールバックをかなり快適に思っていますが、これが私のシナリオに入る方法ではないと私は思います。基本的に私は、main processが作業を続けている間に、私は一つずつ処理する必要がある反復的な高価な仕事（worker）を持っています。ここに最小限のテストです。

/* 
* We have a worker function that does some expensive task, e.g., an 
* I/O task or something else. 
*/ 
worker = function (jobId) { 

    // It will take something between 1 and 2 seconds. 
    var runtime = Math.floor((Math.random() * 1000) + 1000); 
    console.log("started job #" + jobId + " (" + runtime + " ms)"); 

    // Then the worker will do something for a while ... 
    setTimeout(
     function() { 
      // .. and at some point it'll be finished. 
      console.log("finished job #" + jobId); 
     }, runtime 
    ); 

}; 

/* 
* We obviously have a main process that meanwhile does other stuff 
* like processed user interactions. In this case we call this until 
* some artificial tickets are used. 
*/ 
mainprocess = function (tickets) { 

    // Simulate some processing time .. 
    var runtime = Math.floor((Math.random() * 500)); 
    setTimeout(
     function() { 
      console.log("main process #" + tickets + " (" + runtime + " ms)"); 
      if (tickets > 0) { 
       tickets--; 
       mainprocess(tickets); 
      } 
     }, runtime 
    ); 
} 

// At some point in the code we create workers and we want to make sure 
// they're processed in the *order of creation* and *one after another* 
// without blocking the main process ... 
for (var i = 1; i <= 10; i++) { 
    worker(i); 
}; 

// ... and the some other stuff will happen for a while! 
mainprocess(10); 

// .. 

コードは、現在、私は本当に知らない

started job #1 (1751 ms) 
started job #2 (1417 ms) 
... 
started job #9 (1050 ms) 
started job #10 (1864 ms) 
main process #10 (142 ms) 
main process #9 (228 ms) 
main process #8 (149 ms) 
main process #7 (88 ms) 
main process #6 (410 ms) 
finished job #9 
finished job #5 
main process #5 (265 ms) 
finished job #2 
main process #4 (270 ms) 
finished job #7 
finished job #3 
finished job #1 
... 
main process #1 (486 ms) 
main process #0 (365 ms) 

...のようなものを出力し、メインプロセスが継続されるように、コードを変更する方法をワーカースレッドがで実行されている間作成順（現在のところ、正しい順序でのみ開始されています）と（順番に並んでいます）（現在はすべて並列）です。希望の出力は..

started job #1 (1384 ms) 
main process #10 (268 ms) 
main process #9 (260 ms) 
main process #8 (216 ms) 
main process #7 (93 ms) 
main process #6 (160 ms) 
main process #5 (269 ms) 
main process #4 (44 ms) 
finished job #1 
started job #2 (1121 ms) 
main process #3 (172 ms) 
main process #2 (170 ms) 
main process #1 (437 ms) 
finished job #2 
started job #3 (1585 ms) 
main process #0 (460 ms) 
finished job #3 
started job #4 (1225 ms) 
finished job #4 
started job #5 (1300 ms) 
finished job #5 

助けてください。

Answer 1

さて、私はそれを理解しました。拡張コードとコメントコードはのjavacriptの組み込みの約束を使用しますが、QまたはBluebirdまたは他のノード互換性のある約束ライブラリでも同じことを達成できます。ノード環境でjquery $.Deferredオブジェクトを使用できないことに注意してください。必要に応じて

/* 
* We have a worker function that does some expensive task, e.g., an 
* I/O task or something else. 
*/ 
worker = function (jobId) { 

    // we need to put it into a new promise object 
    return new Promise(function(resolve, reject) { 

     // It will take something between 1 and 2 seconds. 
     var runtime = Math.floor((Math.random() * 1000) + 1000); 
     console.log("started job #" + jobId + " (" + runtime + " ms)"); 

     // Then the worker will do something for a while ... 
     setTimeout(
      function() { 
       // .. and at some point it'll be finished. 
       console.log("finished job #" + jobId); 
       // .. now we have to resolve the promise!! 
       resolve("resolved job #" + jobId); 
      }, runtime 
     ); 

    }); 
}; 


/* 
* We obviously have a main process that meanwhile does other stuff 
* like processed user interactions. In this case we call this until 
* some artificial tickets are used. 
*/ 
mainprocess = function (tickets) { 

    // Simulate some processing time .. 
    var runtime = Math.floor((Math.random() * 500)); 
    setTimeout(
     function() { 
      console.log("main process #" + tickets + " (" + runtime + " ms)"); 
      if (tickets > 0) { 
       tickets--; 
       mainprocess(tickets); 
      } 
     }, runtime 
    ); 
} 

// create a sequence with a resolved promise 
var sequence = Promise.resolve(); 

// At some point in the code we create workers and we want to make sure 
// they're processed in the *order of creation* and *one after another* 
// without blocking the main process ... 
for (var i = 1; i <= 10; i++) { 
    // create an IIFE so that the current "i" gets its own 
    // closure when it will be used later (otherwise all job ids 
    // would be "11" on invokation of the worker). 
    (function() { 
     var jobId = i; 
     // add a new promise after the previous promise resolved 
     sequence = sequence.then(
      function(result) { 
       // handle result later 
       return worker(jobId); 
       // return just added the next promise to the chain! 
      }, 
      function(err) { 
       // handle error later 
      } 
     ); 
    })(); // END IIFE 
}; 

// ... and the some other stuff will happen for a while! 
mainprocess(10); 

// .. 

出力は次のようになります。

started job #1 (1384 ms) 
main process #10 (268 ms) 
main process #9 (260 ms) 
main process #8 (216 ms) 
main process #7 (93 ms) 
main process #6 (160 ms) 
main process #5 (269 ms) 
main process #4 (44 ms) 
finished job #1 
started job #2 (1121 ms) 
main process #3 (172 ms) 
main process #2 (170 ms) 
main process #1 (437 ms) 
finished job #2 
started job #3 (1585 ms) 
main process #0 (460 ms) 
finished job #3 
started job #4 (1225 ms) 
finished job #4 
started job #5 (1300 ms) 
finished job #5 
... 

私は洞察を提供し、以下の記事に大きな賛辞を与えることがあります。

• JavaScript promises - There and back again
• We have a problem with promises
• General promise resources (for further reading)

Answer 2

最初にメインスレッドを実行し、作成した順番でワーカースレッドを実行する場合は、ワーカー（i）を呼び出す場所のループをセットタイムアウト関数に配置し、約1000ms。その後、完成したジョブにも1000msの一定の遅延が与えられ、作成された順序で実行されます。 リンクを確認してください：jsfiddle.net/som99/weq87xnd/2/