Basically I want a thread local storage which may be accessed very frequently. I estimate the performance of 2 ways of doing this: use C's __thread to declare a thread local storage, use C functions to access them from Rust. For this, I pay for the cost of functions calls. use Rust's thread_local…

Sorry, my mistake. Yes, the C compiler did optimize the loop away. But still Rust's thread_local!() runs slower than the version of using C thread local from Rust. I am wondering if there is a better way to achieve thread local.

I suspect this might be because you call borrow_mut on every loop iteration. I'm pretty sure the RefCell isn't necessary in this case.

Another thing you might want to try (only on nightly): #![feature(thread_local)] #[thread_local] static mut RUST_THREAD_LOCAL: ThreadLocal = ThreadLocal{i: 0};

It seems I cannot have mut thread_locals with release version. Is there a cheaper way to get mutability other than RefCell? I will try the nightly version.

Cell<T> is cheaper and simpler, when you can use it.

If I remember correct, Cell is for Copy type only. I personally think using RefCell with dynamic borrow for a thread local variable doesn't quite make sense, since there shouldn't be any race contention for a thread local thing. However, it seems there is no other way.

RefCell doesn't have anything to do with race conditions - mutable aliasing is an issue even in a single threaded context: let mut foo = Some(1i32); let i = foo.as_ref().unwrap(); println!("{}", i); // prints 1 foo = None; println!("{}", i); // now what? While the borrow checker will statically…

Rust thread_local bad performance?

help

sfackler January 22, 2016, 7:08am 2

Are you sure the C version isn't just optimizing the for loop out completely into a 12499997500000 literal?

Is there a way to adding to the format string options?

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Rust thread_local bad performance?

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