Bumpalo Rust crate
Ranked 3 of 4 memory allocators by recommenders
A Rust arena allocator that heavy users rely on, praised for fitting Rust's lifetimes and borrow checker. Some commenters call the surrounding allocator ecosystem relatively immature.
A Rust arena allocator that heavy users rely on, praised for fitting Rust's lifetimes and borrow checker. Some commenters call the surrounding allocator ecosystem relatively immature.
10 people gave an opinion
- recommend it
- 8
- criticize it
- 2
- approval share
- 80%
Recommended in 5 of 13 months
- November 2025: not recommended
- December 2025: recommended
- January 2026: not recommended
- February 2026: not recommended
- March 2026: not recommended
- April 2026: not recommended
- May 2026: not recommended
- June 2026: recommended
- July 2026: recommended
- August 2026: not recommended
- September 2026: recommended
- October 2026: recommended
- November 2026: not recommended (month in progress)
Why it doesn’t carry the badge
- 8 people recommend itNeeds 10 or more, not met.
- 4 recommenders for every criticNeeds 2 to 1 or better, met.
- Recommended in 5 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
Fits Rust lifetimes and borrow checker
“arenas benefit greatly from lifetimes, because lifetimes allow them to uphold the usual Rust safety guarantees”
Comment from 19 Sep 2026 in “What Zig felt like, coming from Rust” “Using the arena allocator's lifetime would have been safe and easy (bumpalo recommends this AFAIK).”
Comment from 20 Oct 2026 in “Tsrs: A Port of TypeScript to Rust” “it's quite easy to use and fits the borrow checker very well”
Comment from 12 Jul 2026 in “Understanding the Odin Programming Language” - Comment from 28 Oct 2026 in “Four Months of Zig”
Easy and safe to use
“Using the arena allocator's lifetime would have been safe and easy (bumpalo recommends this AFAIK).”
Comment from 20 Oct 2026 in “Tsrs: A Port of TypeScript to Rust” “Using the arena allocator's lifetime would have been safe and easy”
Comment from 20 Oct 2026 in “Tsrs: A Port of TypeScript to Rust” “it's quite easy to use and fits the borrow checker very well”
Comment from 12 Jul 2026 in “Understanding the Odin Programming Language” Heavily used and reached for by default
“I've been having an absolutely great time with Rust's bumpalo crate, which works very similarly.”
Comment from 5 Dec 2025 in “Why we built Lightpanda in Zig” “I'd still reach for something like Bumpalo unless I had good reason to avoid it.”
Comment from 5 Dec 2025 in “Thoughts on Go vs. Rust vs. Zig” “you do not need to sell me on bumpalo, I use it heavily already”
Comment from 28 Oct 2026 in “Four Months of Zig”
What people warn about
Each mark is one comment
Allocator ecosystem seen as immature
“Rust allows you to drop in non free-list based allocators and GCs (e.g. Bumpalo), but they're relatively immature.”
Comment from 3 Jun 2026 in “Every Byte Matters”
Other memory allocators people recommend
The three most recommended other memory allocators, 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.
See all 4 memory allocators, rankedWhat people said
12 of the 13 comments that mention it, newest first. Each links to the original comment.
“carrying a bump everywhere was useless”
“you do not need to sell me on bumpalo, I use it heavily already”
“which work gloriously well with Rust's lifetime system”
“Using the arena allocator's lifetime would have been safe and easy (bumpalo recommends this AFAIK).”
“Using the arena allocator's lifetime would have been safe and easy”
“the dropping plays well with arena as long as you use bumpalo::boxed::Box”
“that's not composable - not only do you need specialised data structures”
“arenas benefit greatly from lifetimes, because lifetimes allow them to uphold the usual Rust safety guarantees”
“it's quite easy to use and fits the borrow checker very well”
“Rust allows you to drop in non free-list based allocators and GCs (e.g. Bumpalo), but they're relatively immature.”
“I've been having an absolutely great time with Rust's bumpalo crate, which works very similarly.”
“I'd still reach for something like Bumpalo unless I had good reason to avoid it.”
Counts come from 1,795,640 Hacker News comments, November 2025 to November 2026. How we count. Report a mistake.