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Futurelock: A subtle risk in async Rust

(rfd.shared.oxide.computer)
421 points bcantrill | 2 comments | | HN request time: 0.491s | source

This RFD describes our distillation of a really gnarly issue that we hit in the Oxide control plane.[0] Not unlike our discovery of the async cancellation issue[1][2][3], this is larger than the issue itself -- and worse, the program that hits futurelock is correct from the programmer's point of view. Fortunately, the surface area here is smaller than that of async cancellation and the conditions required to hit it can be relatively easily mitigated. Still, this is a pretty deep issue -- and something that took some very seasoned Rust hands quite a while to find.

[0] https://github.com/oxidecomputer/omicron/issues/9259

[1] https://rfd.shared.oxide.computer/rfd/397

[2] https://rfd.shared.oxide.computer/rfd/400

[3] https://www.youtube.com/watch?v=zrv5Cy1R7r4

1. ideaformlabs ◴[] No.45779328[source]
It’s kind of wild how even the most careful Rust code can run into issues like this, really shows how deep async programming goes.
replies(1): >>45780136 #
2. 24f0bacc7c72d0a ◴[] No.45780136[source]
This is why I use a threadpool instead. Cant deal with the complexity of async code.