tokio 1.54.1

An event-driven, non-blocking I/O platform for writing asynchronous I/O backed applications.
Documentation 
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#![cfg(all(
    target_os = "emscripten",
    not(target_feature = "atomics"),
    feature = "rt",
    feature = "macros"
))]

/// There is no threadpool on a single-threaded JS worker: the public
/// `spawn_blocking` is unsupported on non-pthread emscripten, as on the other
/// single-threaded wasm targets. `tokio::fs` and
/// `tokio::io::{stdin, stdout, stderr}` do not rely on it there — their
/// syscalls complete synchronously.
#[tokio::test]
#[should_panic = "OS can't spawn worker thread"]
async fn spawn_blocking_is_unsupported() {
    let _ = tokio::task::spawn_blocking(|| 42).await;
}