Struct YieldNow 

pub struct YieldNow(/* private fields */);

Future that yields once, then completes.

Returns Pending on first poll, wakes itself, completes on second poll. Other ready tasks get a turn before this task resumes.

Caveat: cross-thread waits

yield_now is a cooperative yield within the executor. It does not park the executor or yield CPU to other OS threads. On a single-threaded runtime, a tight wait loop like

while !cross_thread_state_ready() {
    yield_now().await;
}

will busy-spin and starve other OS threads (a tokio worker thread, an Aeron media driver, a separate sender thread) of CPU. The producer can’t fire its wake in time, the loop appears hung even though the external work would have completed eventually.

For cross-thread waits, use a parking primitive instead:

• await rx.recv() on a channel — parks until the sender wakes
• await notify.notified() on a Notify — parks until notify_one()
• mix yield_now with periodic sleep — bounded park gives the OS time to schedule producer threads

Trait Implementations

impl Future for YieldNow

type Output = ()

The type of value produced on completion.

fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<()>

Attempts to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.