fix: error instead of busy-looping when write returns Ok(0)#921
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seanmonstar merged 1 commit intoJul 16, 2026
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This fixes a bug we saw in production. There's a nasty interaction between `h2` and the `ktls` crate. Namely: 1. When the write-side of the connection is closed, the `ktls` crate returns `Ok(0)` instead of an error. 2. `h2` retries `Ok(0)` writes, instead of treating them as errors. This led to busy looping, and 100% CPU utilization. Ideally, this should be fixed in both the `h2` and `ktls` crates, but I'm targeting `h2` first because of its central place in the ecosystem. This fix mirrors existing logic in hyper HTTP/1: https://github.com/hyperium/hyper/blob/v1.10.1/src/proto/h1/io.rs#L285-L297
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Oof. Makes sense to me, thanks for the fix!
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This fixes a bug we saw in production. There's a nasty interaction between
h2and thektlscrate. Namely:ktlscrate returnsOk(0)instead of an error.h2retriesOk(0)writes, instead of treating them as errors.This led to busy looping, and 100% CPU utilization. Ideally, this should be fixed in both the
h2andktlscrates, but I'm targetingh2first because of its central place in the ecosystem.This fix mirrors existing logic in hyper HTTP/1: https://github.com/hyperium/hyper/blob/v1.10.1/src/proto/h1/io.rs#L285-L297