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Comment by smitherfield | Hacker News Reader

"As before, values stored on the stack are scanned conservatively"

Why would values on the stack be garbage-collected at all? Do they mean scanning the stack for live references?

I read this as "if it is on the stack and looks like a reference when you squint your eyes, then we treat it as a reference" compared to objects on the heap where the GC seems to know the exact location of all references.

Right that's the standard conservative garbage collection. However, new results show that it's significantly worse than a precise collector (reference pending).

I'd love to see that reference, as I've not yet seen an example where this was true in practicd, but know several examples where it is definitely false (e.g. we use a modification of the Julia GC which uses consevative stack scanning to allow interop with another system, and it seems to perform very well).

I think that only scanning the stack conservatively should not change much from a completely precise GC. The chances of misidentifying a potential reference to an enormous data structure that is collectable are pretty slim in a memory region as small as a typical stack.

Scanning the entire heap is different because of its generally much bigger size. It's far more likely then to see references where there are none.

Sorry for the late follow up. Hopefully you're still around to notice. Apparently there was previous HN discussion on this, but I haven't seen it (or looked for it): https://www.excelsiorjet.com/blog/articles/conservative-gc-i...

Scanned, not collected. Specifically, scanned recursively to mark embedded objects as alive.

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