Limit Promise Concurrency with pool

By  on  

Methods like Promise.all, Promise.allSettled, Promise.race, and the rest are really excellent for managing multiple Promises, allowing for our apps to embrace async and performance. There are times, however, that limiting the number of concurrent operations may be useful, like rate limiting or simply not wanting to put a server under massive stress.

Enter an simple utility for limiting Promise concurrency: pool!

import pool from '@ricokahler/pool';

async function getQuotes() {
  const quotes = await pool({
    collection: [1, 2, 3, 4, 5],
    maxConcurrency: 2, // Limit 2 requests at a time
    task: async (symbol) => {
      const response = await fetch(`/quotes/${symbol}`);
      const json = await response.json();
      return json;
    },
  });

  console.log(quotes); // Array of the 5 quotes
}

pool lets you specify how many requests to run concurrently. If no concurrency value is provided, pool acts like Promise.all.

Concurrency is an important issue with JavaScript's async nature, so having a method for pooling them together and limiting concurrent actions is important.

Recent Features

  • By
    Designing for Simplicity

    Before we get started, it's worth me spending a brief moment introducing myself to you. My name is Mark (or @integralist if Twitter happens to be your communication tool of choice) and I currently work for BBC News in London England as a principal engineer/tech...

  • By
    Create a CSS Flipping Animation

    CSS animations are a lot of fun; the beauty of them is that through many simple properties, you can create anything from an elegant fade in to a WTF-Pixar-would-be-proud effect. One CSS effect somewhere in between is the CSS flip effect, whereby there's...

Incredible Demos

  • By
    CSS Text Overlap

    One of the important functions of CSS is to position elements. Margin, padding, top, left, right, bottom, position, and z-index are just a few of the major players in CSS positioning. By using the above spacing...

  • By
    pointer Media Query

    As more devices emerge and differences in device interaction are implemented, the more important good CSS code will become.  In order to write good CSS, we need some indicator about device capabilities.  We've used CSS media queries thus far, with checks for max-width and pixel ratios.

Discussion

    Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!