Rayon
Hacker ApprovedRanked 2 of 8 Rust crates by recommenders
People recommend it for adding multicore parallelism to Rust code with very little effort, and for its safe, simple parallel iterators. Critics say its abstractions are sometimes not flexible enough.
People recommend it for adding multicore parallelism to Rust code with very little effort, and for its safe, simple parallel iterators. Critics say its abstractions are sometimes not flexible enough.
20 people gave an opinion
- recommend it
- 18
- criticize it
- 2
- approval share
- 90%
Recommended in 10 of 13 months
- November 2025: recommended
- December 2025: recommended
- January 2026: recommended
- February 2026: recommended
- March 2026: recommended
- April 2026: recommended
- May 2026: recommended
- June 2026: not recommended
- July 2026: recommended
- August 2026: recommended
- September 2026: not recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it carries the badge
- 18 people recommend itNeeds 10 or more, met.
- 9 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 10 of 13 monthsNeeds 4 or more, met.
The same three rules apply to every product, and the badge can’t be bought. How the badge works
What people say about it
The reasons people give, with the number of comments that give each one. Open a reason to read what they said.
Why people recommend it
Each mark is one comment
Easy parallelism with minimal code
“It's shockingly easy to make a single-threaded Rust program use all the cores on a machine by slapping in Rayon”
Comment from 11 Oct 2026 in “Valen's Memory Safety: A New Kind of Borrow Checking” “The Rust library was fully multithreaded in an afternoon by importing Rayon behind a cargo feature”
Comment from 19 Jan 2026 in “Fil-Qt: A Qt Base build with Fil-C experience” “made jumping from hello world to parallel/concurrent execution pretty simple”
Comment from 3 Feb 2026 in “When rust ≠ performance. a lesson in developer experience” - Comment from 5 Feb 2026 in “Show HN: Toktrack – 1000x faster AI CLI cost tracker (Rust and SIMD)”
Safe, fearless concurrency in Rust
“Rust's type system also allows you to make safe interfaces like Rayon that do genuinely allow for "fearless" concurrency”
Comment from 11 Oct 2026 in “Valen's Memory Safety: A New Kind of Borrow Checking” “For what I do I rarely need mutexes, instead either rayon or message passing work well.”
Comment from 13 Oct 2026 in “Valen's Memory Safety: A New Kind of Borrow Checking” Fast for CPU-bound workloads
“We use rayon where cache locality penalty is minor compared to the millisecond latency gains”
Comment from 16 Jul 2026 in “The Tokio/Rayon Trap and Why Async/Await Fails Concurrency” “My decade-old PC can sort 2 billion hashes in about 30 seconds using the Rust "Rayon" crate.”
Comment from 8 Nov 2025 in “Two billion email addresses were exposed” “I have mostly written intra-node code for which rayon has been adequate.”
Comment from 17 Apr 2026 in “30 Years of HPC: many hardware advances, little adoption of new languages” Great multi-processing experience overall
“rayon is the most amazing multi-processing experience I've ever had!”
Comment from 9 May 2026 in “Bun's experimental Rust rewrite hits 99.8% test compatibility on Linux x64 glibc” “Rayon sort of is that dream for CPU thread pools!”
Comment from 28 Jan 2026 in “Rust's Standard Library on the GPU”
What people warn about
Each mark is one comment
Not flexible enough for some uses
“the libraries just don't work for what we want to use it for”
Comment from 16 Jul 2026 in “The Tokio/Rayon Trap and Why Async/Await Fails Concurrency” “the abstractions are not always flexible/convenient enough”
Comment from 16 Jul 2026 in “The Tokio/Rayon Trap and Why Async/Await Fails Concurrency”
Other Rust crates people recommend
The four most recommended other Rust crates, with the same counts for each, so you can compare like for like. The tick on each bar marks the 2 to 1 line the badge needs.
| Product | Recommend | Criticize | Approval | Months | Owned | Badge |
|---|---|---|---|---|---|---|
| anyhow (Rust crate) | 34 | 10 | 77% | 5 | — | Approved |
| RayonThis page | 18 | 2 | 90% | 10 | — | Approved |
| thiserror | 16 | 8 | 67% | 5 | — | Approved |
| rand crate | 9 | 3 | 75% | 4 | — | — |
| Facet (Rust reflection library) | 6 | 2 | 75% | 4 | — | — |
What people said
All 20 comments that mention it, newest first. Each links to the original comment.
“For what I do I rarely need mutexes, instead either rayon or message passing work well.”
“Rust's type system also allows you to make safe interfaces like Rayon that do genuinely allow for "fearless" concurrency”
“It's shockingly easy to make a single-threaded Rust program use all the cores on a machine by slapping in Rayon”
“This ended up working fine”
“Here is an interesting video about it”
“the abstractions are not always flexible/convenient enough”
“We use rayon where cache locality penalty is minor compared to the millisecond latency gains”
“It solved a runtime starvation issue for us at work, spawn_blocking did not work.”
“calling Tokio + Rayon bad because they explicitly don't do this is a bit of a miss”
“the libraries just don't work for what we want to use it for”
“rayon is the most amazing multi-processing experience I've ever had!”
“which presumably has some overhead”
“I have mostly written intra-node code for which rayon has been adequate.”
“Since you're using Rayon for the multicore side”
“Dead simple parallel processing.”
“made jumping from hello world to parallel/concurrent execution pretty simple”
“Rayon sort of is that dream for CPU thread pools!”
“The Rust library was fully multithreaded in an afternoon by importing Rayon behind a cargo feature”
“I skipped the root cause analysis and kept the original rayon design.”
“My decade-old PC can sort 2 billion hashes in about 30 seconds using the Rust "Rayon" crate.”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.