[brabel]

Yeah that is a junior mistake... They should've pre-sized the ArrayList, or better, used an array because that's more memory efficient (and I would say would be what any decent dev would do when the size of tasks is known beforehand).

> Some folks pointed out that in Rust (tokio) it can use a loop iterating over the Vec instead of join_all to avoid the resize to the list

Right, but some folks also pointed out you should've used an array in Java in the previous blog post, 2 years ago, and you didn't do that.

And folks also pointed out Elixir shouldn't have used Task in the previous benchmark (folk here being the creator of Elixir himself): https://github.com/pkolaczk/async-runtimes-benchmarks/pull/7

[sfn42]

The difference between an arraylist with correct initial size and an array is almost nothing. Arraylist itself is just a wrapper around an array.

[brabel]

It can be a big difference if boxing is involved. Or if the list is very big, because all access to items in the list require casting at the bytecode level (due to type erasure).