main.rs

use rayon::prelude::*;

fn main() {
    std::thread_local!(static CLIENT: std::cell::RefCell<Option<reqwest::Client>> = std::cell::RefCell::new(None));
    rayon::ThreadPoolBuilder::new()
        .num_threads(8)
        .build_scoped(
            |thread| {
                CLIENT.with(|c| {
                    *c.borrow_mut() = Some(reqwest::Client::new());
                });
                thread.run()
            },
            |pool| {
                pool.install(|| {
                    (0..20).into_par_iter().for_each(|_| {
                        CLIENT.with(|ref_client| {
                            let client = ref_client.borrow();
                            let client = client.as_ref().unwrap();
                            let mut rt = tokio::runtime::Runtime::new().unwrap();
                            rt.block_on(async {
                                let resp = client.get("https://google.com").send().await.unwrap();
                                let status = resp.status();
                                let body = resp.text().await.unwrap();
                                println!("{} {}", status, body.len());
                            });
                        });
                    });
                })
            },
        )
        .unwrap();
}