maximum Set size in Node 24 vs Node 23. 16M vs 8M

[KatSick]

Version

24.10.0

Platform

Darwin local 24.6.0 Darwin Kernel Version 24.6.0: Mon Aug 11 21:16:21 PDT 2025; root:xnu-11417.140.69.701.11~1/RELEASE_ARM64_T6000 arm64

Subsystem

No response

What steps will reproduce the bug?

Run

const infiniteSet = new Set();
let counter = 0;

for (; counter < 10000000000; counter++) {
    infiniteSet.add(`item-${counter}`);

    if (counter % 1000 === 0) {
        console.log(`Set size: ${infiniteSet.size}`);
    }
}

on Node 23 and Node 24 and Node 25.

on Node 25 - ~16M items
on Node 24 - ~8M items
on Node 23 - ~16M items

How often does it reproduce? Is there a required condition?

100% of the cases

What is the expected behavior? Why is that the expected behavior?

Same maximum Set size

What do you see instead?

Reduced Set max size in half

Additional information

vs

[ChALkeR]

Looks like a v8 bug (fixed upstream), that also affects Array and Map

Cleaner testcase:

let i

console.log(`Node.js ${process.version}`)

const arr = []
try {
  for (i = 0; i < 1e10; i++) arr.push(0) 
} catch {
  console.log(`Array stopped at ${i.toLocaleString()}`)
}
arr.length = 0

const set = new Set()
try {
  for (i = 0; i < 1e10; i++) set.add(i)
} catch {
  console.log(`Set stopped at ${i.toLocaleString()}`)
}
set.clear()

const map = new Map()
try {
  for (i = 0; i < 1e10; i++) map.set(i, 0)
} catch {
  console.log(`Map stopped at ${i.toLocaleString()}`)
}
map.clear()

Node.js v22.21.0
Array stopped at 112,813,858
Set stopped at 16,777,216
Map stopped at 16,777,216

Node.js v24.0.0
Array stopped at 67,108,864
Set stopped at 8,388,608
Map stopped at 8,388,608

Node.js v24.10.0
Array stopped at 67,108,864
Set stopped at 8,388,608
Map stopped at 8,388,608

Node.js v25.0.0
Array stopped at 134,217,728
Set stopped at 16,777,216
Map stopped at 16,777,216

v8 bug report for arrays (fixed): https://issues.chromium.org/issues/417413670

cc @targos @nodejs/v8 perhaps

[richardlau]

Related to #58197?

[ChALkeR]

@richardlau Array is definitely that.
As for Map/Set, I can't confirm without applying the patch that it's fixed by the exact same commits

[ChALkeR]

I would propose to merge these bugs anyway and use the unified testcase from #60461 (comment)

If we fix it by cherry-picking we should fix all of arrays/maps/sets.
All of those appeared in 24.0.0, all of those are fixed upstream and in 25.0.0, and the size changes look identical

[ChALkeR]

Applied the change and re-checked.
This is the exact same issue as #58197, with a common fix

Node.js v24.10.1-pre
Array stopped at 67108864
Set stopped at 8388608
Map stopped at 8388608

Node.js v24.10.1-pre
Array stopped at 134217728
Set stopped at 16777216
Map stopped at 16777216