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Subsecond: A runtime hotpatching engine for Rust hot-reloading

(docs.rs)
217 points varbhat | 3 comments | 24 Jun 25 18:58 UTC | HN request time: 0.432s | source
1. cyberax ◴[25 Jun 25 03:37 UTC] No.44373433[source]▶
Can we have the same for Go, pretty please?
replies(2): >>44373563 #>>44377546 #
2. ◴[25 Jun 25 04:14 UTC] No.44373563[source]▶
3. mdaniel ◴[25 Jun 25 14:09 UTC] No.44377546[source]▶
> The gist of it is that we intercept the Rust linking phase and then drive `rustc` manually. There's some diffing logic that compares assembly between compiles and then a linking phase where we patch symbols against the running process

makes it sound like it's actually not super rust specific, just a ton of squinting at assembly dumps. I do wonder if there are some "reproducible builds" traps hiding in this, but maybe it just needs to be selective about what it patches, and that turns out to be the really hard problem

I didn't follow the tick() problem cited elsewhere, but my mental model is that, sure, one should not patch currently executing code without expecting "well that didn't do what I wanted" type shenanigans