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0 pointsjosephg7h ago0 comments

> If it's doing a drop in the hot loop that may be an unexpected performance regression that could be carefully lifted.

Yeah, I've heard of people being surprised that when they make massive collections of Box'ed entries, then get surprised that it takes a long time to Drop the whole thing. But this would be the same in C or Zig too. Malloc and free are really complex functions. Reducing heap allocations is an essential tool for optimisation.

The solution to this "unexpected performance regression" in rust is the same as it is in C, C++ and Zig: Stop heap allocating so much. Use primitive types, SSO types (SmartString and friends in rust) or memory arenas. Drop isn't the problem.

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brabel3h ago

In zig the solution is to use an arena allocator. That’s about as easy as it gets. Maybe Rust also allows doing that, I don’t know.

staticassertionnew7m ago

You can use arenas in Rust, it's just not as trivial to swap allocators generally. But there are plenty of crates for it.

j / k navigate · click thread line to collapse

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brabel3h ago

In zig the solution is to use an arena allocator. That’s about as easy as it gets. Maybe Rust also allows doing that, I don’t know.

staticassertionnew7m ago

You can use arenas in Rust, it's just not as trivial to swap allocators generally. But there are plenty of crates for it.

j / k navigate · click thread line to collapse