docs: example of CPU core pinning

actix-web/examples/worker-cpu-pin.rs

@@ -0,0 +1,41 @@
+use std::{
+    io,
+    sync::{
+        atomic::{AtomicUsize, Ordering},
+        Arc,
+    },
+    thread,
+};
+
+use actix_web::{middleware, web, App, HttpServer};
+
+async fn hello() -> &'static str {
+    "Hello world!"
+}
+
+#[actix_web::main]
+async fn main() -> io::Result<()> {
+    env_logger::init_from_env(env_logger::Env::new().default_filter_or("info"));
+
+    let core_ids = core_affinity::get_core_ids().unwrap();
+    let n_core_ids = core_ids.len();
+    let next_core_id = Arc::new(AtomicUsize::new(0));
+
+    HttpServer::new(move || {
+        let pin = Arc::clone(&next_core_id).fetch_add(1, Ordering::AcqRel);
+        log::info!(
+            "setting CPU affinity for worker {}: pinning to core {}",
+            thread::current().name().unwrap(),
+            pin,
+        );
+        core_affinity::set_for_current(core_ids[pin]);
+
+        App::new()
+            .wrap(middleware::Logger::default())
+            .service(web::resource("/").get(hello))
+    })
+    .bind(("127.0.0.1", 8080))?
+    .workers(n_core_ids)
+    .run()
+    .await
+}