promise-parallelizer

PromiseParallelizer

promise-parallelizer

A lightweight library to parallelize promises.

• Features
• Installation
• Methods signatures
• Loading the module
• Common Usage
  • BATCH mode
  • STREAMING mode
• License

Features

• Concurrency management ( scale the parallel promise executions according to the concurrency amount )
• Batch mode ( wait for all of the batch promises to complete before execute a new batch of promises )
• Streaming mode ( execute the promises as soon as the executing promises amount is under the concurrency parameter )
• Delay management between consecutives executions ( either between next batches or between next promise depending on the mode )
• Intermediary callback ( invoke a callback with the intermediary execution result at each batch end or promise end depending on the mode )

Installation

$ npm install promise-parallelizer

Methods signatures

function parallelize(tasks, mode = "STREAMING", concurrency = 1, delay = 0, callback = null) Promise({ started: int, ended: int })

Loading the module

const promiseParallelizer = require('promise-parallelizer');

Common Usage

Parallelize promises in BATCH mode

const mode = "BATCH"
const concurrency = 3;
const tasks = [1,2,3,4,5,6].map(function(index) {
  return function () {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        counter++;
        resolve(index);
      }, 1000 * (index % 3 +1));
    });
  };
});

Standard

(async function() {
  // all of the promises should be resolved after 6 seconds in BATCH mode
  const result = await promiseParallelizer.parallelize(tasks, "BATCH", 3);
})();

Using delay

(async function() {
  // all of the promises should be resolved after 8 seconds in BATCH mode ( 2 seconds delay between consecutive batches)
  const result = await promiseParallelizer.parallelize(tasks, "BATCH", 3, 2);
})();

Using callback

(async function() {
  // callback should log 2 times the intermediary result in BATCH mode  ( once after each batch )
  const result = await promiseParallelizer.parallelize(tasks, "BATCH", 3, 0, (intermediaryResult) => {
    console.log("intermediary result : " + intermediaryResult)
  });
})();

Parallelize promises in STREAMING mode

const mode = "STREAMING"
const concurrency = 3;
const tasks = [1,2,3,4,5,6].map(function(index) {
  return function () {
    return new Promise((resolve, reject) => {
      setTimeout(() => {
        counter++;
        resolve(index);
      }, 1000 * (index % 3 +1));
    });
  };
})

Standard

(async function() {
  // all of the promises should be resolved after 5 seconds in STREAMING mode
  const result = await promiseParallelizer.parallelize(tasks, "STREAMING", 3);
})();

Using delay

(async function() {
  // all of the promises should be resolved after 6 seconds in STREAMING mode ( 2 seconds delay to flush after a promise ends)
  const result = await promiseParallelizer.parallelize(tasks, "STREAMING", 3, 2);
})();

Using callback

(async function() {
  // callback should log 6 times the intermediary result in STREAMING mode  ( once at each promise resolution )
  const result = await promiseParallelizer.parallelize(tasks, "STREAMING", 3, 0, (intermediaryResult) => {
    console.log("intermediary result : " + intermediaryResult)
  });
})();

License

MIT