1540986 - Dead zones are not automatically collected

Status: NEW

(Core :: JavaScript: GC, defect, P3)

Description

[Jon Coppeard (:jonco)]

The following script causes the shell to allocate 10GB of memory without triggering a collection by allocating memory in many different zones:

for (let i = 0; i < 1000; i++) {
    let g = newGlobal({newCompartment: true});
    g.eval(`
        let size = 10 * 1024 * 1024;
        let a = new Int8Array(10 * 1024 * 1024)
        for (let i = 0; i < size; i += 4096) {
            a[i] = i;
        }
    `);
}

The memory ends up unreachable but per-zone allocation thresholds are not reached so no GC is triggered.

I think might be what is causing OOMs in our testing. Even if not it suggests we should have some kind of trigger based on the number of zones.

Comment 1

[Jon Coppeard (:jonco)]

(In reply to Jon Coppeard (:jonco) from comment #0)

I think might be what is causing OOMs in our testing.

I wrote a patch for this and it doesn't help. I now suspect OOMs during reftests are caused by a memory leak.