How does tokio task spawn connect to the executor?

v1yd0r67gk30 · November 25, 2024, 5:06am

hi, I was wondering how tokio task spawn actually sends the task to the executor if run. How does it connect to tokio::main exactly? Does the macro create syntax sugar around it? How is the executor in scope to receive the task?

parasyte · November 25, 2024, 5:15am

If you're asking how tokio::task::spawn() knows which executor is available, it's currently using thread-local storage. This is an implementation detail that is subject to change. But that's how it works today.

github.com

tokio-rs/tokio/blob/c07257f99f92c5d6773fc0827bcfd77e43f0fd46/tokio/src/runtime/context.rs#L78


      
                  tokio_unstable,
                  tokio_taskdump,
                  feature = "rt",
                  target_os = "linux",
                  any(target_arch = "aarch64", target_arch = "x86", target_arch = "x86_64")
              ))]
              trace: trace::Context,
          }
          
          tokio_thread_local! {
              static CONTEXT: Context = const {
                  Context {
                      #[cfg(feature = "rt")]
                      thread_id: Cell::new(None),
          
                      // Tracks the current runtime handle to use when spawning,
                      // accessing drivers, etc...
                      #[cfg(feature = "rt")]
                      current: current::HandleCell::new(),
          
                      // Tracks the current scheduler internal context

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How does tokio task spawn connect to the executor?

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