promise-limiter

Simultaneous Promise Execution Limiter

Motivation

PromiseLimiter takes less memory resource. PromiseLimiter does not use a queue of Promise to restrict the number of executions. PromiseLimiter uses await to block rest of promises. So it takes less memory even if the length of the array bellow is large or using infinite ReadableStream.

Installation

Install by npm from this GitHub repository

npm install -S git+https://github.com/nwtgck/promise-limiter-npm#v0.1.0

Usage

Here is an usage.

const promiseLimiter = new PromiseLimiter(3);
for(const millis of [800, 100, 500, 200, 1000, 400]) {
  const {promise} = await promiseLimiter.run(async () => {
    console.log(`Start: ${millis}`);
    // Sleep for millis
    await new Promise(resolve => setTimeout(resolve, millis));
    console.log(`  Finish: ${millis}`);
    return `Result: ${millis}`;
  });
}

Console log is the following.

Start: 800
Start: 100
Start: 500
  Finish: 100
Start: 200
  Finish: 200
Start: 1000
  Finish: 500
Start: 400
  Finish: 800
  Finish: 400
  Finish: 1000

You can use promise in const {promise} = ... to get fulfilled result of async () => {...} in run().