Comment by ktpsns

15 hours ago

I find the arena experiment very interesting. If done right, whole programs can be structured as as a set of arenas. I've read some things on arenas here such as https://news.ycombinator.com/item?id=37670740

I am a low-level zig guy right now too. I have been around for a long time, and it’s funny to see arenas come back into vogue as a solution to nearly everything.

Arenas are great for avoiding allocations per tick/request/frame/layer. No symmetric free() to bracket lifetimes! They have a purpose, and we always knew that.

But by definition, your program is over-allocating as a tradeoff. Makes a ton of sense in certain use cases. However, we didn’t invent garbage collection and borrow-checking and realloc() just to publish papers ;)

Half of my time programming zig is spent considering allocation strategies. That’s a feature. “Where are the bytes?”

  • We invented those strategies when we had way less RAM. Vast majority of programs could be entirely allocated upfront those days.

    • The reason why so many programs could be allocated upfront is because if they couldn’t, maybe we just didn’t write the program.

Once allocators in general click, memory management in C becomes a total breeze.

Combined with typed fat pointers (slices and strings), typed hashmaps and stack-trace-assertions, C in general becomes quite nice. The rest is compiler flags.

Go solves this by being a better language out of the box, but with the Wirthian aspects removed they feel very similar. Perhaps not so surprising.

I wonder if they can solve the "ecosystem fracture" issue by borrowing the bubble concept from e.g. testing/synctest. The way the synctest API works is by creating a "bubble" around the test harness and the code under test such that the standard library's time package behaves differently, but only for the code running in the bubble.

So, maybe we could also have allocator bubbles, where code running inside the bubble is just as allocator-naive as any other Go code, but when it allocates (make/new/pointer escape), it uses the bubble's allocator instead of the default one.

The big problem I can think of, though, which doesn't apply to time bubbles, would be that pointers drawn from that allocator might escape the bubble (e.g. by assigning them to a longer-lived struct field). It's possibly something that can be detected by the runtime, but because the API is non-invasive by design, it's not something that will be apparent to the programmer when looking at the code.