Async Rust memory reuse

async_memory_reuse.rs

use tokio::select;
use tokio::time::{sleep, Duration};

struct CanDrop {
    a: Vec<i32>,
}

impl Drop for CanDrop {
    fn drop(&mut self) {
        println!("Dropping!")
    }
}

async fn memory_hungry() {
    let mut x = Box::new(CanDrop {
        a: vec![0; 90_PERCENT_OF_SYSTEM_RAM],
    });
    println!("memory_hungry() starting sleep");
    sleep(Duration::from_secs(2)).await;
    println!("memory_hungry() finished sleep");
    x.a[0] = 1;  // Use the data so as to avoid any optimizations that elide it
}

#[tokio::main]
async fn main() {
    println!("Starting select");
    select! {
        _ = memory_hungry() => unreachable!(),
        _ = sleep(Duration::from_secs(1)) => println!("slept 1"),
    }
    println!("Done with select");
    memory_hungry().await;
}