Benchmark: async for vs promise all (setTimeout version)

Script Preparation code:

function emptyTimeout(ms) {
    return new Promise((resolve, reject) =>
        setTimeout(() => resolve(), ms));
}

async function asyncFor() {
  for (let i = 50; i < 500; i += 50) {
    await emptyTimeout(i);
  }
}

async function asyncPromiseAll() {
  const promises = [];
  for (let i = 50; i < 500; i += 50) {
    promises.push(emptyTimeout(i));
  }
  await Promise.all(promises);
}

Tests:

asyncFor
asyncFor()
asyncPromiseAll
asyncPromiseAll()

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
asyncFor
asyncPromiseAll

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/108.0.0.0 Safari/537.36

Browser/OS: Chrome 108 on Windows

View result in a separate tab

Test name	Executions per second
asyncFor	19950.9 Ops/sec
asyncPromiseAll	732.8 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

Let's break down the provided benchmark definition and test cases.

**Benchmark Definition:**

The benchmark measures the performance of two approaches to iterate over an array asynchronously:

1. `asyncFor()`: This approach uses an asynchronous for loop, which iterates over the array using a traditional for loop but yields control to other tasks (like `setTimeout`) at each iteration.
2. `asyncPromiseAll()`: This approach uses Promise.all, which executes an array of promises and waits for all of them to resolve before continuing.

**Options Compared:**

The two approaches are compared in terms of execution time. The benchmark aims to determine which approach is faster for this specific use case.

**Pros and Cons:**

1. `asyncFor()`:
	* Pros: Can be more efficient when dealing with large arrays because it doesn't create multiple promises, reducing memory usage.
	* Cons: May not be as readable or maintainable due to the use of async/await syntax and traditional for loop.
2. `asyncPromiseAll()`:
	* Pros: More concise and readable code. It's easier to understand what the function does at a glance.
	* Cons: Creates multiple promises, which can lead to higher memory usage and slower execution times due to the overhead of creating and managing promises.

**Library Used:**

None explicitly mentioned in the benchmark definition, but it uses Promises, which are built into JavaScript. Promises are used as a way to handle asynchronous operations in a more manageable and readable way.

**Special JS Feature or Syntax:**

The benchmark uses async/await syntax, which is a modern feature introduced in ECMAScript 2017 (ES7). Async/await allows developers to write asynchronous code that looks like synchronous code, making it easier to read and maintain.

**Other Considerations:**

When writing this benchmark, the author likely considered factors such as:

* Execution time: The benchmark focuses on measuring how long each approach takes to complete.
* Memory usage: The use of promises in `asyncPromiseAll()` may lead to higher memory usage due to the creation of multiple promises.
* Readability and maintainability: The choice of approach affects how easy it is for developers to understand and modify the code.

**Alternatives:**

Other approaches to iterate over an array asynchronously might include:

1. `forEach()`: This method executes a callback function once for each element in an array, without creating promises.
2. Generators: A generator function can be used to create an iterator that yields values one at a time, which can be used with a loop or other async/await approaches.
3. Iterators: JavaScript's built-in iterators allow developers to create custom iteration mechanisms, potentially offering better performance than the approaches tested in this benchmark.

Keep in mind that these alternatives might have different trade-offs and may not offer significant improvements over the tested approaches.

Related benchmarks:

async for vs promise all (setTimeout version) (version: 0)

Inspired by: https://www.measurethat.net/Benchmarks/Show/13019/0/async-for-vs-promiseall

Comparing performance of: asyncFor vs asyncPromiseAll

Created: 4 years ago by: Guest

Jump to the latest result

asyncFor

asyncPromiseAll

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):