tokio-0.2-0.3 thread panicked at 'there is no reactor running, must be called from the context of Tokio runtime'

Cargo.toml

[package]
name = "hello-tokio"
version = "0.1.0"
authors = ["smallfish"]
edition = "2018"

[dependencies]
tokio = { version = "0.2", features = ["full"] }
#tokio = { version = "0.3", features = ["full"] }
actix-web = "3.0.2"
reqwest = { version = "0.10", features = ["json"] }
thiserror = "1.0"
log = "0.4"
env_logger = "0.8"

main.rs

use actix_web::{web, App, HttpServer, Responder};
use reqwest;
use std::thread;
use std::thread::sleep;
use thiserror::Error;
use tokio::time::Duration;

const ADDR: &str = "0.0.0.0:8081";

#[derive(Error, Debug)]
enum MyError {
    #[error("reqwest error")]
    ReqwestError(#[from] reqwest::Error),
}

async fn index() -> impl Responder {
    "index"
}

async fn check_health(url: &str) -> Result<u16, MyError> {
    let client = reqwest::Client::new().get(url).send().await?;
    Ok(client.status().as_u16())
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {
    env_logger::init();
    
    let url = format!("http://{}", ADDR);
    thread::spawn(move || {
        let mut rt = tokio::runtime::Runtime::new().unwrap();
        loop {
            sleep(Duration::from_secs(3));
            let result = rt.block_on(check_health(url.as_str()));
            log::info!("check {:?} health {:?}", url, result);
        }
    });

    HttpServer::new(|| App::new().route("/", web::get().to(index)))
        .bind(ADDR)?
        .run()
        .await
}

change tokio version 0.2 to 0.3

$ RUST_BACKTRACE=1 RUST_LOG=info cargo run
...
thread '<unnamed>' panicked at 'there is no reactor running, must be called from the context of Tokio runtime'..
stack backtrace:
   0: rust_begin_unwind
...