How to handle 'Send' trait violations in async Rust with tokio?
I'm trying to debug I'm dealing with I'm having trouble with I'm maintaining legacy code that I'm currently working on a Rust application using the `tokio` runtime (version 1.0) and working with issues related to the `Send` trait when trying to spawn tasks that use a shared state. I have a struct that implements `Arc<Mutex<MyState>>`, but when I attempt to pass it to an async function, I encounter the following behavior: ``` behavior[E0277]: the trait bound `MyState: Send` is not satisfied --> src/main.rs:20:5 | 20 | tokio::spawn(async move { | ^^^^^^^^^^^^^^ the trait `Send` is not implemented for `MyState` | = note: the `Send` trait is required because this value will be moved across thread boundaries = note: consider using `Arc<Mutex<MyState>>` or `Arc<RwLock<MyState>>` to share state safely ``` My `MyState` struct is defined as follows: ```rust struct MyState { value: i32, } ``` I understand that `Send` is not implemented for `MyState`, but I thought wrapping it in `Arc<Mutex<MyState>>` would solve the question. I've tried different approaches, including adding `#[derive(Sync)]` and `#[derive(Send)]`, but to no avail. Here’s the relevant piece of code: ```rust use std::sync::{Arc, Mutex}; use tokio::task; struct MyState { value: i32, } #[tokio::main] async fn main() { let my_state = Arc::new(Mutex::new(MyState { value: 0 })); let state_clone = my_state.clone(); task::spawn(async move { let mut state = state_clone.lock().unwrap(); state.value += 1; }); } ``` I'm unsure if I’m missing some configuration or if there's a deeper scenario with my struct. Any guidance on how to resolve this `Send` trait violation would be greatly appreciated! This is part of a larger service I'm building. Any help would be greatly appreciated! This is my first time working with Rust 3.9. This is part of a larger web app I'm building. I'm on Ubuntu 22.04 using the latest version of Rust. Cheers for any assistance! I'd be grateful for any help.