p-all

What is p-all?

The p-all package is a utility module for running multiple promise-returning & async functions with limited concurrency, aggregating the results. It is useful for controlling the execution of a large number of asynchronous operations to ensure that system resources are managed properly.

What are p-all's main functionalities?

Running multiple promises with limited concurrency

This feature allows you to run multiple promises with a specified concurrency limit. In the code sample, three tasks are executed with a concurrency limit of 2, meaning only two promises will be running at the same time.

const pAll = require('p-all');

const tasks = [
  () => Promise.resolve('Task 1'),
  () => Promise.resolve('Task 2'),
  () => Promise.resolve('Task 3')
];

pAll(tasks, { concurrency: 2 }).then(results => {
  console.log(results); // ['Task 1', 'Task 2', 'Task 3']
});

Other packages similar to p-all

bluebird

Bluebird is a comprehensive promise library with a wide range of features including concurrency control. It offers similar functionality through its 'Promise.map' method with a 'concurrency' option. Bluebird is known for its performance and additional utilities for promise manipulation.

async

The async library provides a collection of asynchronous utilities. Its 'parallelLimit' function can be used to achieve similar concurrency control as p-all. Async is not promise-based by default but supports promises and also provides other flow control utilities.

p-limit

p-limit is a package that limits the number of concurrent promise executions, similar to p-all. The difference is that p-limit provides a lower-level API where you create a limiter function and then apply it to individual promises, whereas p-all takes an array of promise-returning functions.

p-queue

p-queue is a promise queue with adjustable concurrency that can be paused, resumed, and cleared. It is more feature-rich than p-all, providing a queue interface with more control over the execution of tasks, including dynamic prioritization and task cancellation.

README

p-all

Run promise-returning & async functions concurrently with optional limited concurrency

Similar to Promise.all(), but accepts functions instead of promises directly so you can limit the concurrency.

If you're doing the same work in each function, use p-map instead.

See p-series for a serial counterpart.

Install

$ npm install p-all

Usage

import pAll from 'p-all';
import got from 'got';

const actions = [
	() => got('https://sindresorhus.com'),
	() => got('https://avajs.dev'),
	() => checkSomething(),
	() => doSomethingElse()
];

console.log(await pAll(actions, {concurrency: 2}));

API

pAll(tasks, options?)

Returns a Promise that is fulfilled when all promises returned from calling the functions in tasks are fulfilled, or rejects if any of the promises reject. The fulfilled value is an Array of the fulfilled values in tasks order.

tasks

Type: Iterable<Function>

Iterable with promise-returning/async functions.

options

Type: object

concurrency

Type: number
Default: Infinity
Minimum: 1

Number of concurrent pending promises.

stopOnError

Type: boolean
Default: true

When set to false, instead of stopping when a promise rejects, it will wait for all the promises to settle and then reject with an aggregated error containing all the errors from the rejected promises.

Related

• p-map - Map over promises concurrently
• p-series - Run promise-returning & async functions in series
• p-props - Like Promise.all() but for Map and Object
• p-queue - Promise queue with concurrency control
• p-limit - Run multiple promise-returning & async functions with limited concurrency
• More…