add test for await

test/await/dune

@@ -1,5 +1,5 @@
 
 (tests
-  (names t_fib1 t_futs1)
+  (names t_fib1 t_futs1 t_many)
   (enabled_if (>= %{ocaml_version} 5.0))
   (libraries moonpool trace tracy-client.trace))

test/await/t_many.ml

@@ -0,0 +1,29 @@
+open Moonpool
+
+let pool = Pool.create ~min:4 ()
+
+let run () =
+  let t1 = Unix.gettimeofday () in
+
+  let n = 1_000_000 in
+  let n_tasks = 10 in
+  let task () =
+    let l = List.init n (fun x -> Fut.spawn ~on:pool (fun () -> x)) in
+    Fut.spawn ~on:pool (fun () ->
+        List.fold_left
+          (fun n x ->
+            let _res = Fut.await_exn x in
+            n + 1)
+          0 l)
+  in
+
+  let futs =
+    List.init n_tasks (fun _ -> Fut.spawn ~on:pool task |> Fut.join ~on:pool)
+  in
+
+  let lens = List.map Fut.wait_block_exn futs in
+  Printf.printf "awaited %d items (%d times)\n%!" (List.hd lens) n_tasks;
+  Printf.printf "in %.4fs\n%!" (Unix.gettimeofday () -. t1);
+  assert (List.for_all (fun s -> s = n) lens)
+
+let () = run ()