Rust: What is the difference between std::sync and tokio::sync?

std::sync — blocking primitives. tokio::sync — async primitives.

std::sync:

• Mutex, RwLock, Condvar.
• Blocking.
• Not for async.

tokio::sync:

• async Mutex, RwLock, Semaphore.
• Non-blocking.
• For async code.

1use tokio::sync::Mutex;
2
3let data = Mutex::new(5);
4
5async fn update(data: &Mutex<i32>) {
6    let mut val = data.lock().await;
7    *val += 1;
8}

Key: Use tokio::sync in async code, std::sync in blocking code.