From 05fae4ed5967aafd70a097d42de101f7d24c69e0 Mon Sep 17 00:00:00 2001
From: Thomas Leonard <talex5@gmail.com>
Date: Thu, 8 Aug 2024 15:43:06 +0100
Subject: [PATCH] Record trace event when spawning processes

This can take quite a long time.
---
 lib_eio_linux/low_level.ml | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib_eio_linux/low_level.ml b/lib_eio_linux/low_level.ml
index 1af99be23..2db0f2fe6 100644
--- a/lib_eio_linux/low_level.ml
+++ b/lib_eio_linux/low_level.ml
@@ -571,7 +571,10 @@ module Process = struct
     let exit_status, set_exit_status = Promise.create () in
     let t =
       Fd.use_exn "errors-w" errors_w @@ fun errors_w ->
-      let pid, pid_fd = eio_spawn errors_w c_actions in
+      let pid, pid_fd =
+        Eio.Private.Trace.with_span "spawn" @@ fun () ->
+        eio_spawn errors_w c_actions
+      in
       let pid_fd = Fd.of_unix ~sw ~seekable:false ~close_unix:true pid_fd in
       { pid; pid_fd; exit_status }
     in