Add benchmarks

Cargo.toml

@@ -22,5 +22,6 @@ vec-arena = "1.0.0"
 
 [dev-dependencies]
 async-channel = "1.4.1"
-async-io = "0.2.0"
+async-io = "1.1.9"
 easy-parallel = "3.1.0"
+num_cpus = "1.13.0"

benches/executor.rs

@@ -0,0 +1,109 @@
+#![feature(test)]
+
+extern crate test;
+
+use std::future::Future;
+
+use async_executor::Executor;
+use futures_lite::future::{self, FutureExt};
+
+const TASKS: usize = 300;
+const STEPS: usize = 300;
+const LIGHT_TASKS: usize = 25_000;
+
+static EX: Executor<'_> = Executor::new();
+
+fn run(f: impl FnOnce()) {
+    let (s, r) = async_channel::bounded::<()>(1);
+    easy_parallel::Parallel::new()
+        .each(0..num_cpus::get(), |_| future::block_on(EX.run(r.recv())))
+        .finish(move || {
+            let _s = s;
+            f()
+        });
+}
+
+#[bench]
+fn create(b: &mut test::Bencher) {
+    b.iter(move || {
+        let ex = Executor::new();
+        let task = ex.spawn(async {});
+        future::block_on(ex.run(task));
+    });
+}
+
+#[bench]
+fn spawn_one(b: &mut test::Bencher) {
+    run(|| {
+        b.iter(move || {
+            future::block_on(async { EX.spawn(async {}).await });
+        });
+    });
+}
+
+#[bench]
+fn spawn_many(b: &mut test::Bencher) {
+    run(|| {
+        b.iter(move || {
+            future::block_on(async {
+                let mut tasks = Vec::new();
+                for _ in 0..LIGHT_TASKS {
+                    tasks.push(EX.spawn(async {}));
+                }
+                for task in tasks {
+                    task.await;
+                }
+            });
+        });
+    });
+}
+
+#[bench]
+fn spawn_recursively(b: &mut test::Bencher) {
+    fn go(i: usize) -> impl Future<Output = ()> + Send + 'static {
+        async move {
+            if i != 0 {
+                EX.spawn(async move {
+                    let fut = go(i - 1).boxed();
+                    fut.await;
+                })
+                .await;
+            }
+        }
+    }
+
+    run(|| {
+        b.iter(move || {
+            future::block_on(async {
+                let mut tasks = Vec::new();
+                for _ in 0..TASKS {
+                    tasks.push(EX.spawn(go(STEPS)));
+                }
+                for task in tasks {
+                    task.await;
+                }
+            });
+        });
+    });
+}
+
+#[bench]
+fn yield_now(b: &mut test::Bencher) {
+    run(|| {
+        b.iter(move || {
+            future::block_on(async {
+                let mut tasks = Vec::new();
+                for _ in 0..TASKS {
+                    tasks.push(EX.spawn(async move {
+                        for _ in 0..STEPS {
+                            future::yield_now().await;
+                        }
+                    }));
+                }
+                for task in tasks {
+                    task.await;
+                }
+            });
+        });
+    });
+}