> On a single machine I can just replace an `.iter()` into a `.par_iter()` in my Rust programs and boom, I parallelized my workload across every core with only

> On a single machine I can just replace an `.iter()` into a `.par_iter()` in my Rust programs and boom, I parallelized my workload across every core with only a single line change. If you’re using Rayon for anything you expect to benefit from a lot of cores, my experiences have been very negative in the past. Rayon is often extremely inefficient once you allow it to use more than a handful of cores.[0] If your unit of work is absolutely massive, you might not be as affected by Rayon’s scheduler, but it makes me sad that this issue still hasn’t been resolved. My comment on that thread (documenting just one instance where I ran into this issue) was almost 4 years ago! And the issue itself is almost a year older than that. Sure, I could try to contribute a general solution, but it’s just easier to stop using Rayon. I no longer consider Rayon to be an advantage for Rust. There are plenty of good ways to wire up a parallel work pool, but they do require more than a one line change. [0]: https://github.com/rayon-rs/rayon/issues/394 https://github.com/rayon-rs/rayon/issues/394