Структура Stdout

// WRONG: creates a new handle each iteration
for i in 0..10 {
    let mut out = io::stdout();
    out.write_all(b"data").await?;
    out.write_all(b"\n").await?;
    // out is dropped here; its last write may still be
    // running when the next iteration starts
}

let mut out = io::stdout();
for i in 0..10 {
    out.write_all(b"data").await?;
    out.write_all(b"\n").await?;
}

use tokio::io::{self, AsyncWriteExt};

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut stdout = io::stdout();
    stdout.write_all(b"Hello world!").await?;
    Ok(())
}

use tokio::io::{self, AsyncWriteExt};

#[tokio::main]
async fn main() {
    let messages = vec!["hello", " world\n"];

    // When you use `stdio` in a loop, it is recommended to create
    // a single `stdio` instance outside the loop and call a write
    // operation against that instance on each loop.
    //
    // Repeatedly creating `stdout` instances inside the loop and
    // writing to that handle could result in mangled output since
    // each write operation is handled by a different blocking thread.
    let mut stdout = io::stdout();

    for message in &messages {
        stdout.write_all(message.as_bytes()).await.unwrap();
        stdout.flush().await.unwrap();
    }
}