Ibarrier primitive?

1

Is there an implementation of a ibarrier in either sync or async Rust?

2

Are you running MPI? If so, there are Rust bindings for MPI_Ibarrier. Tokio has a Barrier type, but it blocks the task till all other tasks have reached the barrier. Since Tokio is an asynchronous runtime I'd say Barrier is something between MPI_Ibarrier and MPI_Barrier in the sense that it does not block the whole process or a thread but only a lightweight task, allowing tokio to process other tasks in the meantime.

1 Like
3

Thanks. A hypothetical ibarrier in tokio would allow the existing async function to make progress though which would be significantly easier to reason about with the borrow checker

4

How do you intend to wait for the non-blocking barrier in async Rust without calling .await at some point? In a busy loop? In general it is considered good practice not to have tasks that are busy for longer periods. To quote from an excellent article about async programming in Rust:

Async code should never spend a long time without reaching an .await.

5

I want something like

let ibarrier = Ibarrier::new(n);
// in async task:
ibarrier.signal();
// do some stuff
ibarrier.wait().await; // completes once n tasks have called `.ibarrier.signal()

If it isn't implemented I can implement it, I just want to know if it is already out there. The "some stuff" might itself call await, and I would be okay with signal being async.