Concurrency Control Libraries Comparison
p-limit vs p-queue vs p-throttle
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What's Concurrency Control Libraries?

Concurrency control libraries in Node.js help manage the execution of asynchronous tasks, ensuring that resources are used efficiently and that operations do not overwhelm the system. These libraries provide mechanisms to limit the number of concurrent operations, queue tasks for execution, or throttle the rate of execution, which is crucial in scenarios like API requests, file processing, or any situation where resource management is essential for performance and stability.

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p-limit125,838,1602,0808.23 kB85 months agoMIT
p-queue6,925,9023,50436 kB46a year agoMIT
p-throttle1,374,01144711.7 kB716 days agoMIT
Feature Comparison: p-limit vs p-queue vs p-throttle

Concurrency Management

  • p-limit:

    p-limit allows you to set a maximum number of concurrent promises, enabling you to control how many tasks can run simultaneously. This is particularly useful for managing resources effectively without queuing tasks, making it lightweight and straightforward for simple concurrency needs.

  • p-queue:

    p-queue provides a more comprehensive approach by managing a queue of tasks. It allows you to set both concurrency limits and prioritize tasks, ensuring that tasks are executed in the order they were added, with options for retries and cancellation, making it suitable for complex workflows.

  • p-throttle:

    p-throttle focuses on limiting the rate at which a function can be executed. It ensures that a function is not called more frequently than a specified interval, making it ideal for scenarios where you need to control the frequency of operations, such as API calls.

Use Cases

  • p-limit:

    p-limit is best suited for scenarios where you have a large number of independent asynchronous tasks that can be executed concurrently, such as fetching multiple resources or processing files without overwhelming the system.

  • p-queue:

    p-queue is ideal for scenarios where tasks need to be executed in a specific order, such as processing jobs in a background worker system or managing API requests that must adhere to a specific sequence or priority.

  • p-throttle:

    p-throttle is perfect for scenarios where you need to prevent excessive calls to a function, such as limiting the number of API requests made in a given timeframe to comply with rate limits imposed by external services.

Error Handling

  • p-limit:

    p-limit does not provide built-in error handling; however, it allows you to handle errors within the individual promise executions, giving you flexibility in managing failures as they occur.

  • p-queue:

    p-queue includes built-in support for error handling, allowing you to retry failed tasks or handle them according to your logic, making it suitable for more complex error management scenarios.

  • p-throttle:

    p-throttle does not inherently manage errors, but it allows you to implement your error handling logic within the throttled function, enabling you to control how errors are processed in a rate-limited context.

Performance

  • p-limit:

    p-limit is lightweight and efficient, making it suitable for high-performance applications where you want to limit concurrency without introducing significant overhead.

  • p-queue:

    p-queue may introduce some overhead due to its queuing mechanism, but it provides better control and management of tasks, which can lead to improved performance in scenarios where order and retries are important.

  • p-throttle:

    p-throttle is designed to optimize performance by controlling the execution rate of functions, ensuring that resources are not overwhelmed, which can lead to better overall application performance.

Learning Curve

  • p-limit:

    p-limit has a low learning curve, making it easy to integrate into existing codebases for developers who need simple concurrency control without additional complexity.

  • p-queue:

    p-queue has a moderate learning curve due to its additional features like prioritization and retries, but it is still relatively straightforward for developers familiar with promise-based patterns.

  • p-throttle:

    p-throttle is easy to understand and implement, especially for developers familiar with function throttling concepts, making it accessible for quick integration into projects.

How to Choose: p-limit vs p-queue vs p-throttle
  • p-limit:

    Choose p-limit when you need to control the maximum number of concurrent promises that can run at the same time. It is ideal for scenarios where you want to limit concurrency without queuing tasks, allowing for immediate execution of tasks up to a specified limit.

  • p-queue:

    Choose p-queue if you need a more robust solution that not only limits concurrency but also manages a queue of tasks. It is useful for scenarios where tasks need to be executed in order and you want to ensure that tasks are retried on failure or managed with priority levels.

  • p-throttle:

    Choose p-throttle when you need to limit the rate of function execution over time. It is particularly useful for scenarios like API rate limiting, where you want to ensure that a function is not called more often than a specified rate, thus preventing overwhelming a service.

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 p-queue

p-queue is a promise-based queue implementation for managing asynchronous tasks in JavaScript. It allows developers to control the concurrency of tasks, ensuring that a specified number of tasks run simultaneously while others wait in line. This is particularly useful when dealing with APIs or other asynchronous operations that may have rate limits or require controlled execution. With features like priority support and the ability to pause and resume queues, p-queue provides a flexible solution for managing complex asynchronous workflows.

There are several alternatives to p-queue that also provide functionality for managing asynchronous tasks:

  • async is a widely-used utility module that provides a variety of functions to work with asynchronous JavaScript. It includes methods for controlling concurrency, such as async.eachLimit and async.parallelLimit, which allow you to run multiple asynchronous operations in parallel with a specified limit. While async is a powerful library with a broad range of features, it may be considered more heavyweight compared to p-queue, especially if you only need simple queuing functionality.

  • p-all is a lightweight utility that allows you to run multiple promise-returning functions concurrently and returns a promise that resolves when all of the promises have resolved. It provides a simple way to manage concurrency without the additional features found in p-queue. If your primary need is to run a set of promises concurrently without the overhead of a full queue implementation, p-all is an excellent choice.

  • p-limit is another minimalist utility that allows you to limit the number of concurrent promises. It creates a function that can be called with promise-returning functions, ensuring that only a specified number of them are executed at any given time. This is particularly useful for controlling resource usage when dealing with APIs or other asynchronous tasks. If you need a straightforward way to limit concurrency without the additional features of a queue, p-limit is an ideal solution.

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

Similar Npm Packages to p-throttle

p-throttle is a utility library that allows developers to limit the number of times a function can be called over a specified period. This is particularly useful in scenarios where you want to prevent overwhelming a server with too many requests or to control the rate of execution of asynchronous functions. By using p-throttle, you can ensure that your application behaves more predictably and efficiently, especially when dealing with resource-intensive operations.

While p-throttle provides a straightforward solution for throttling function calls, there are alternative libraries that also offer similar functionality. Here are a couple of noteworthy alternatives:

  • limiter is a flexible library that provides rate limiting for asynchronous functions. It allows you to define how many times a function can be called within a specific timeframe, making it suitable for scenarios where you need to control the rate of execution. limiter is particularly useful for managing API calls or other resource-intensive operations, ensuring that your application remains responsive and efficient. Its simple API and customizable options make it a strong contender for developers looking for a robust rate-limiting solution.

  • p-limit is another library that helps you limit the number of concurrent promises. Unlike p-throttle, which focuses on throttling the execution rate of a single function, p-limit allows you to control how many promises can run simultaneously. This can be particularly useful when you want to manage the load on a server or optimize the performance of your application by preventing too many concurrent operations. With p-limit, you can easily set the concurrency level, making it a great choice for handling multiple asynchronous tasks efficiently.

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

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)

Returns a limit function.

concurrency

Type: number
Minimum: 1
Default: Infinity

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.

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…
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