Nowadays nobody should use locks anyway, as there are much better, faster and safer variants for concurrency with native threads, based on actor capabilities and ownership, and avoid blocking IO like hell. No, not Rust. Rust did it wrong.
Those who do it right are so far Pony, Midori/Singularity, and parrot with native kernel threads. With simple green threads there are some more, but they are only usable for fast IO, not fast CPU tasks.