From c30f3b1c0c6956958a1892184d69dbc77ee7c7b8 Mon Sep 17 00:00:00 2001
From: Shon Feder <shon.feder@gmail.com>
Date: Sun, 7 Sep 2025 10:44:04 -0400
Subject: [PATCH] Fix possible data races in eio test bin

Since this test runs with multiple domains, we cannot mutate plain refs
as we were without inviting data races.
---
 tests/bin/emit1_eio.ml | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tests/bin/emit1_eio.ml b/tests/bin/emit1_eio.ml
index 83a9481e..9990b227 100644
--- a/tests/bin/emit1_eio.ml
+++ b/tests/bin/emit1_eio.ml
@@ -11,22 +11,22 @@ let sleep_outer = ref 2.0
 
 let n_jobs = ref 1
 
-let num_sleep = Atomic.make 0
-
 let stress_alloc_ = ref true
 
+let num_sleep = Atomic.make 0
+
 let stop = Atomic.make false
 
 let num_tr = Atomic.make 0
 
 (* Counter used to mark simulated failures *)
-let i = ref 0
+let i = Atomic.make 0
 
 let run_job clock _job_id iterations : unit =
   let@ scope =
     Atomic.incr num_tr;
     OT.Trace.with_ ~kind:OT.Span.Span_kind_producer "loop.outer"
-      ~attrs:[ "i", `Int !i ]
+      ~attrs:[ "i", `Int (Atomic.get i) ]
   in
 
   for j = 0 to iterations do
@@ -52,7 +52,7 @@ let run_job clock _job_id iterations : unit =
               ~severity:Severity_number_info "inner at %d" j;
           ]);
 
-      incr i;
+      Atomic.incr i;
 
       try
         Atomic.incr num_tr;
@@ -68,7 +68,7 @@ let run_job clock _job_id iterations : unit =
         let () = Eio.Time.sleep clock !sleep_inner in
         Atomic.incr num_sleep;
 
-        if j = 4 && !i mod 13 = 0 then failwith "oh no";
+        if j = 4 && Atomic.get i mod 13 = 0 then failwith "oh no";
 
         (* simulate a failure *)
         Opentelemetry.Scope.add_event scope (fun () ->