JavaScript Concurrency Control Libraries Comparison
p-limit vs async vs bottleneck vs rate-limiter-flexible vs promise-limit
Search packages..
1 Year
p-limitasyncbottleneckrate-limiter-flexiblepromise-limitSimilar Packages:
What's JavaScript Concurrency Control Libraries?

These libraries provide various mechanisms for managing asynchronous operations in JavaScript, particularly focusing on concurrency control, rate limiting, and promise management. They help developers handle multiple asynchronous tasks efficiently, ensuring that performance is optimized while avoiding issues such as overwhelming a server with requests or running too many operations simultaneously. Each library has its unique approach and use cases, making them suitable for different scenarios in web development.

NPM Package Downloads Trend
Github Stars Ranking
Stat Detail
Package
Downloads
Stars
Size
Issues
Publish
License
p-limit120,146,0952,08710.3 kB62 days agoMIT
async55,464,37828,209808 kB64 months agoMIT
bottleneck2,805,2701,837-865 years agoMIT
rate-limiter-flexible625,1523,100141 kB192 months agoISC
promise-limit339,421143-106 years agoISC
Feature Comparison: p-limit vs async vs bottleneck vs rate-limiter-flexible vs promise-limit

Concurrency Control

  • p-limit:

    p-limit offers a simple API to limit the number of concurrent promises. It allows you to specify how many promises can run at the same time, making it easy to manage resource consumption without complicating your codebase.

  • async:

    Async provides a variety of methods for controlling concurrency, allowing you to run multiple asynchronous operations in series, parallel, or in a waterfall manner. This flexibility makes it suitable for complex workflows where the order of execution matters.

  • bottleneck:

    Bottleneck focuses specifically on rate limiting and concurrency control, allowing you to set limits on how many times a function can be called in a given timeframe. This is particularly useful for API calls where you need to avoid exceeding rate limits imposed by the server.

  • rate-limiter-flexible:

    Rate Limiter Flexible offers advanced concurrency control features, allowing you to define complex rate limiting rules and manage them dynamically. It supports various storage options for tracking usage, making it suitable for high-traffic applications.

  • promise-limit:

    Promise Limit provides a straightforward way to limit concurrent promises, ensuring that only a specified number of promises are active at any time. This helps in managing system resources effectively without introducing unnecessary complexity.

Ease of Use

  • p-limit:

    p-limit is lightweight and straightforward, making it easy to use for developers who need basic concurrency control without the overhead of a larger library. Its simplicity is one of its key strengths.

  • async:

    Async has a steeper learning curve due to its extensive feature set and various control flow methods. However, once mastered, it provides powerful tools for managing asynchronous operations effectively.

  • bottleneck:

    Bottleneck is designed to be user-friendly, with a simple API that allows developers to quickly implement rate limiting without a lot of boilerplate code. It’s easy to integrate into existing projects.

  • rate-limiter-flexible:

    Rate Limiter Flexible is slightly more complex due to its advanced features, but it provides comprehensive documentation that helps developers implement sophisticated rate limiting strategies.

  • promise-limit:

    Promise Limit is very easy to implement and understand, making it suitable for developers looking for a quick solution to limit concurrent promises without additional complexity.

Performance

  • p-limit:

    p-limit is designed for performance, allowing you to run a specified number of promises concurrently without unnecessary overhead. This makes it an efficient choice for managing promise execution.

  • async:

    Async can introduce overhead due to its extensive feature set, but it is optimized for performance in handling multiple asynchronous operations. Careful management of control flow can lead to efficient execution of tasks.

  • bottleneck:

    Bottleneck is highly performant, as it allows you to control the rate of function calls without significant overhead. It efficiently manages the timing of calls to ensure optimal performance while adhering to rate limits.

  • rate-limiter-flexible:

    Rate Limiter Flexible is built for performance in high-traffic applications, providing efficient rate limiting without compromising on speed. Its ability to work with various storage backends allows for scalable solutions.

  • promise-limit:

    Promise Limit is optimized for performance, ensuring that limiting concurrent promises does not introduce significant delays or resource consumption, making it suitable for high-load scenarios.

Use Cases

  • p-limit:

    p-limit is well-suited for tasks that involve a large number of asynchronous operations, such as processing files or making network requests, where you want to control how many run at once to avoid overwhelming the system.

  • async:

    Async is ideal for complex workflows where multiple asynchronous operations need to be coordinated, such as data processing pipelines or when working with multiple APIs that require specific execution orders.

  • bottleneck:

    Bottleneck is perfect for scenarios where you need to limit the rate of API requests, such as when interacting with third-party services that impose strict rate limits on their endpoints.

  • rate-limiter-flexible:

    Rate Limiter Flexible is best for applications that require strict rate limiting across distributed systems, such as web applications that need to manage user requests to prevent abuse or overloading services.

  • promise-limit:

    Promise Limit is great for simple use cases where you need to limit concurrent promises without additional overhead, such as executing multiple database queries or API calls in a controlled manner.

Flexibility

  • p-limit:

    p-limit is flexible in its simplicity, allowing developers to easily adjust the concurrency limit without complex configurations, making it a good choice for straightforward use cases.

  • async:

    Async offers a high degree of flexibility with its various methods for managing asynchronous control flow, allowing developers to choose the best approach for their specific use case.

  • bottleneck:

    Bottleneck provides flexibility in defining rate limits and can be easily configured to adapt to different scenarios, making it versatile for various applications.

  • rate-limiter-flexible:

    Rate Limiter Flexible is highly configurable, allowing developers to define complex rate limiting strategies that can adapt to changing application requirements.

  • promise-limit:

    Promise Limit offers flexibility in managing concurrent promises, allowing developers to quickly adapt the number of active promises based on application needs.

How to Choose: p-limit vs async vs bottleneck vs rate-limiter-flexible vs promise-limit
  • p-limit:

    Opt for p-limit if you need a lightweight solution to limit the number of concurrent promises. It's particularly useful when you want to control the concurrency of asynchronous operations without the overhead of a larger library. This is ideal for scenarios where you have a large number of promises to execute but want to limit how many run simultaneously.

  • async:

    Choose Async if you need a comprehensive utility library for working with asynchronous JavaScript, particularly if you require a variety of control flow patterns (like series, parallel, and waterfall) and want to manage callbacks effectively. It's ideal for projects that involve complex asynchronous workflows.

  • bottleneck:

    Select Bottleneck if your primary concern is to limit the rate of function calls, especially in scenarios where you need to control the number of requests sent to an API or any other resource. It provides a simple and flexible way to ensure that your application does not exceed a specified rate limit while maintaining performance.

  • rate-limiter-flexible:

    Choose Rate Limiter Flexible if you need a robust solution for rate limiting with support for various storage backends (like Redis, in-memory, etc.) and advanced features such as dynamic rate limiting. This library is perfect for applications that require strict control over the rate of requests, especially in distributed systems.

  • promise-limit:

    Use Promise Limit if you require a straightforward way to limit the number of concurrent promises, similar to p-limit but with a focus on simplicity and ease of use. It’s suitable for scenarios where you want to ensure that only a certain number of promises are active at any given time without complex configurations.

Similar Npm Packages to p-limit

p-limit is a utility library that allows developers to limit the number of concurrent promises that can be executed at a time. This is particularly useful when dealing with APIs or other asynchronous operations where you want to avoid overwhelming the server or hitting rate limits. By using p-limit, you can control the flow of asynchronous tasks, ensuring that only a specified number of them run concurrently, while the others wait in line until a slot becomes available.

While p-limit is a great tool for managing concurrency, there are other libraries that provide similar functionality. Here are a couple of alternatives:

  • p-queue is a promise queue that allows you to manage the concurrency of asynchronous tasks. It provides a more feature-rich solution than p-limit, with options for prioritizing tasks, setting a maximum concurrency level, and even handling retries. If you need more control over the order and execution of your asynchronous operations, p-queue is an excellent choice. It’s particularly useful for scenarios where you need to manage complex workflows or prioritize certain tasks over others.

  • p-throttle is another alternative that focuses on limiting the rate at which a function can be called. Unlike p-limit, which limits concurrent executions, p-throttle allows you to control how often a function can be invoked over time. This can be particularly useful for scenarios like API rate limiting, where you want to ensure that a function is not called too frequently. If your primary concern is controlling the rate of function execution rather than managing concurrency, p-throttle is the right tool for the job.

To see how p-limit compares with p-queue and p-throttle, check out the comparison: Comparing p-limit vs p-queue vs p-throttle.

Similar Npm Packages to async

async is a utility module that provides powerful functions for working with asynchronous JavaScript. It simplifies the process of managing asynchronous operations, allowing developers to write cleaner and more maintainable code. With features like parallel execution, series execution, and control flow, async is particularly useful for handling complex asynchronous workflows. However, there are several alternatives in the JavaScript ecosystem that also provide similar functionalities. Here are a few notable ones:

  • bluebird is a fully-featured promise library that offers a wide range of utilities for working with promises. It enhances the native Promise functionality by providing additional features such as cancellation, progress tracking, and more robust error handling. bluebird is known for its performance and is a great choice for developers looking for an advanced promise library that can handle complex asynchronous tasks with ease.

  • p-map is a lightweight utility that allows you to map over an array asynchronously, executing a provided function for each element in parallel. It is particularly useful when you need to perform asynchronous operations on an array of items and want to control the concurrency level. p-map is simple to use and can be a great alternative for scenarios where you need to process multiple asynchronous tasks without the overhead of a larger library.

  • q is another promise library that focuses on providing a simple and straightforward API for working with asynchronous code. It was one of the earlier promise libraries in the JavaScript ecosystem and offers features like chaining, error handling, and more. While it may not be as feature-rich as some of the newer libraries, q is still a solid choice for developers looking for a lightweight solution for managing asynchronous operations.

To see how async compares with bluebird, p-map, and q, check out the comparison: Comparing async vs bluebird vs p-map vs q.

Similar Npm Packages to bottleneck

bottleneck is a powerful rate-limiting library for JavaScript that helps manage the execution of asynchronous tasks. It allows developers to control how many tasks are executed concurrently and to set limits on the rate at which tasks can be processed. This can be particularly useful when dealing with APIs that have rate limits or when you want to prevent overwhelming a server with too many requests at once. Bottleneck provides a flexible and easy-to-use API for managing these constraints, making it a popular choice for developers looking to optimize their asynchronous workflows.

Here are some alternatives to bottleneck:

  • async is a utility module that provides powerful functions for working with asynchronous JavaScript. It offers a variety of methods for managing asynchronous control flow, including parallel execution, series execution, and more. While async does not specifically focus on rate limiting, it provides a robust set of tools for handling asynchronous operations, making it a versatile choice for many developers. If you need a comprehensive toolkit for managing asynchronous tasks beyond just rate limiting, async is a solid option.
  • p-limit is a simple and lightweight library that allows you to limit the number of concurrent promises. It provides a straightforward API for controlling the concurrency of asynchronous operations, making it easy to prevent overwhelming resources or APIs. If you are looking for a minimalistic solution specifically focused on limiting concurrency, p-limit is a great choice that integrates well with promise-based workflows.
  • promise-limit is another library designed to limit the number of concurrent promises. It offers a simple API for managing the execution of asynchronous functions, allowing you to specify how many promises can run simultaneously. If you need a straightforward way to control concurrency without the additional features of a more complex library, promise-limit can be an effective solution.
  • rate-limiter-flexible is a flexible and powerful rate-limiting library that can be used in both Node.js and browser environments. It allows you to implement various rate-limiting strategies, such as limiting requests per second, minute, or hour. This library is particularly useful for applications that require advanced rate-limiting capabilities, such as those interacting with APIs that enforce strict rate limits.

To see how bottleneck compares with async, p-limit, promise-limit, and rate-limiter-flexible, check out the comparison: Comparing async vs bottleneck vs p-limit vs promise-limit vs rate-limiter-flexible.

Similar Npm Packages to rate-limiter-flexible

rate-limiter-flexible is a powerful and flexible rate-limiting library for Node.js applications. It allows developers to implement rate-limiting strategies to control the number of requests a user can make to an API or service within a specified time frame. This is particularly useful for protecting APIs from abuse, ensuring fair usage, and maintaining performance under high load. The library supports various storage backends, including in-memory, Redis, and MongoDB, making it adaptable to different application architectures.

While rate-limiter-flexible is a robust solution, there are several alternatives available in the Node.js ecosystem that also provide rate-limiting capabilities. Here are a few notable ones:

  • bottleneck is a powerful rate-limiting library that allows you to control the rate of function execution. It provides features such as concurrency control, priority queues, and scheduling, making it suitable for scenarios where you need to manage the execution of asynchronous tasks. If your application requires more than just simple request limiting and you need to manage the execution of functions or tasks, bottleneck is an excellent choice.

  • express-rate-limit is a middleware for Express applications that provides basic rate-limiting functionality. It is easy to set up and configure, making it a popular choice for developers using the Express framework. If you are looking for a straightforward solution to limit the number of requests to your Express routes, express-rate-limit is a simple and effective option.

  • limiter is another lightweight rate-limiting library for Node.js. It provides a simple API for limiting the rate of function calls and can be easily integrated into existing applications. If you need a minimalistic approach to rate limiting without the overhead of more complex libraries, limiter can be a suitable choice.

To compare these libraries and see how they stack up against each other, check out the comparison: Comparing bottleneck vs express-rate-limit vs limiter vs rate-limiter-flexible.

README for p-limit

p-limit

Run multiple promise-returning & async functions with limited concurrency

Works in Node.js and browsers.

Install

npm install p-limit

Usage

import pLimit from 'p-limit';

const limit = pLimit(1);

const input = [
	limit(() => fetchSomething('foo')),
	limit(() => fetchSomething('bar')),
	limit(() => doSomething())
];

// Only one promise is run at once
const result = await Promise.all(input);
console.log(result);

API

pLimit(concurrency) default export

Returns a limit function.

concurrency

Type: number
Minimum: 1

Concurrency limit.

limit(fn, ...args)

Returns the promise returned by calling fn(...args).

fn

Type: Function

Promise-returning/async function.

args

Any arguments to pass through to fn.

Support for passing arguments on to the fn is provided in order to be able to avoid creating unnecessary closures. You probably don't need this optimization unless you're pushing a lot of functions.

limit.activeCount

The number of promises that are currently running.

limit.pendingCount

The number of promises that are waiting to run (i.e. their internal fn was not called yet).

limit.clearQueue()

Discard pending promises that are waiting to run.

This might be useful if you want to teardown the queue at the end of your program's lifecycle or discard any function calls referencing an intermediary state of your app.

Note: This does not cancel promises that are already running.

limit.concurrency

Get or set the concurrency limit.

limitFunction(fn, options) named export

Returns a function with limited concurrency.

The returned function manages its own concurrent executions, allowing you to call it multiple times without exceeding the specified concurrency limit.

Ideal for scenarios where you need to control the number of simultaneous executions of a single function, rather than managing concurrency across multiple functions.

import {limitFunction} from 'p-limit';

const limitedFunction = limitFunction(async () => {
	return doSomething();
}, {concurrency: 1});

const input = Array.from({length: 10}, limitedFunction);

// Only one promise is run at once.
await Promise.all(input);

fn

Type: Function

Promise-returning/async function.

options

Type: object

concurrency

Type: number
Minimum: 1

Concurrency limit.

FAQ

How is this different from the p-queue package?

This package is only about limiting the number of concurrent executions, while p-queue is a fully featured queue implementation with lots of different options, introspection, and ability to pause the queue.

Related

  • p-throttle - Throttle promise-returning & async functions
  • p-debounce - Debounce promise-returning & async functions
  • p-all - Run promise-returning & async functions concurrently with optional limited concurrency
  • More…
Terms & PrivacyProduct HuntJSON to TypeScriptCopilotChat for Web Dev