prelude: don't set Lwt_engine to poll if libev is available (#52)

yasunariw · web-flow · commit 8bb7d7f79944 · 2025-11-25T06:34:25.000+08:00
diff --git a/prelude.ml b/prelude.ml
@@ -55,5 +55,12 @@ let call_me_maybe f x =
   | None -> ()
   | Some f -> f x
 
+(*
+  If libev backend is available, do nothing (lwt uses it as default).
+  Otherwise, prefer poll over select, because select can only monitor fds up to 1024,
+  and poll is guaranteed to be available without the fd limitation.
+*)
 let () =
-  Lwt_engine.set @@ new Lwt_engines.poll
+  if not (Lwt_config._HAVE_LIBEV && Lwt_config.libev_default) then begin
+    Lwt_engine.set @@ new Lwt_engines.poll
+  end
