BUG: concurrent mode 'task' crashes node process. FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory

[Zombobot1]

Use case

I want to benchmark how my server (runs on aws) performs (a stress test).
I need to run certain number of concurrent requests from my machine to this server. For example, I want to run 100 concurrent requests (tasks) for 60 seconds.

I tried to test how it might work using settings from the docs

from docs

import { Bench } from 'tinybench';

const bench = new Bench({ time: 100 });

bench
  .add('faster task', () => {
    console.log('I am faster')
  })
  .add('slower task', async () => {
    await new Promise(r => setTimeout(r, 1)) // we wait 1ms :)
    console.log('I am slower')

// options way (recommended)
bench.threshold = 10 // The maximum number of concurrent tasks to run. Defaults to Infinity.
bench.concurrency = "task" // The concurrency mode to determine how tasks are run.  
// await bench.warmup()
await bench.run()

// standalone method way
// await bench.warmupConcurrently(10, "task")
await bench.runConcurrently(10, "task") // with runConcurrently, mode is set to 'bench' by default

it crushes during warmup or run.

Reproduction

I cloned repo to debug this test

import Bench from "src";
import { test, expect, vi } from "vitest";

test("should run concurrently using default time and iterations", async () => {
  const bench = new Bench();

  bench.add("foo", async () => 1);

  bench.concurrency = "task";
  bench.threshold = 2;

  await bench.run(); // FATAL ERROR: Reached heap limit Allocation failed - JavaScript heap out of memory
});

I found that it runs this line promises.push(limit(executeTask)); runs endlessly because while condition is always true:
while (totalTime < time || ((samples.length + limit.activeCount + limit.pendingCount) < iterations)). Specifically: totalTime < time where totalTime = 0 and time = 500.

I can fix my problem by using time: 0, warmupTime: 0, in options like it is done in your tests. I find it to be confusing. If I misconfigured a benchmark it should throw an error instead of leaking memory until it crashes.

After Theo promoted your library as benchmark js replacement I think it should have a more friendly api for concurrent tests (or more comprehensive docs) for wider adoption.

[Aslemammad]

That's an amazing reproduciton, do you have a potential fix you may want to send a PR for?

[jerome-benoit]

One can compare each tasks against the noop benchmark and if it's below it, adapt the default settings.