Runtime Memory Usage Experiment

Today, I had this crazy question if comments inside js functions consume more memory than comments outside of them?

This was based on the theory that function().toString() preserves full function body, including comments:

function fn() {
  return "Lorem ipsum dolor sit amet";
}

/*
function fn() {
  return "Lorem ipsum dolor sit amet";
}
*/
console.log(fn.toString());

Running benchmarks, I was proven wrong. But still worth sharing benchmark scripts, especially comparing Node.js, Deno, and Bun timing and memory consumption differences.

Results

Benchmarks running on MBA M2 on Battery with MacOS 14 Beta (23A5286i).

You can run it yourself by cloning this repository and running ./bench.sh script.

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Testing ./fixtures/inline.mjs on Node v18.16.0

Stage	Time	Rss	HeapTotal	HeapUsed	External	ArrayBuffers
Init	0ms	37.91 MiB	6.08 MiB	5.12 MiB	414.05 KiB	19.97 KiB
Imported	5.57ms	+9.66 MiB	+4.73 MiB	+4.77 MiB	+4.72 MiB	+4.72 MiB
Imported (x2)	5.68ms	+16 KiB	+0 Bytes	+14.67 KiB	+0 Bytes	+0 Bytes
Called	7.7ms	+0 Bytes	+0 Bytes	+768 Bytes	+0 Bytes	+0 Bytes

Testing ./fixtures/inline.mjs on Deno v1.36.3

Stage	Time	Rss	HeapTotal	HeapUsed	External
Init	0ms	35.27 MiB	9.73 MiB	8.78 MiB	75.01 KiB
Imported	6ms	+14.39 MiB	+4.73 MiB	+4.72 MiB	+0 Bytes
Imported (x2)	6ms	+0 Bytes	+0 Bytes	+1.63 KiB	+0 Bytes
Called	8ms	+32 KiB	+0 Bytes	+792 Bytes	+0 Bytes

Testing ./fixtures/inline.mjs on Bun v0.8.1

Stage	Time	Rss	HeapTotal	HeapUsed	External	ArrayBuffers
Init	0ms	18.63 MiB	805 KiB	0 Bytes	0 Bytes	0 Bytes
Imported	19.73ms	+7.84 MiB	+32 KiB	313.45 KiB	0 Bytes	0 Bytes
Imported (x2)	19.76ms	+0 Bytes	+0 Bytes	+0 Bytes	0 Bytes	0 Bytes
Called	19.76ms	+0 Bytes	+0 Bytes	+0 Bytes	0 Bytes	0 Bytes