fix(concurrency): shadow loop variable in event handler goroutine

Create local copy of loop variable before passing to goroutine to prevent handlers from capturing wrong event due to loop variable mutation.

commit: 196ef1eb281e20edb0feb5fa9a3cf4c1e40542be
author: brice · 8mo ago · 2026-02-06 05:56 UTC
parent: e62cfa8
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

1 file · +5 -4

M internal/adapters/out/eventbus/inmemory.go +5 -4


@@ -186,11 +186,12 @@ func (bus *InMemory) handleEvent(event domain.Event) {
186	186
187	187		for _, handler := range handlers {
188	188		if handler.CanHandle(event.Type) {
	189	+	h := handler // shadow loop variable for goroutine capture
189	190		start := time.Now()
190	191
191	192		done := make(chan error, 1)
192	193		go func() {
193		-	done <- handler.Handle(event)
	194	+	done <- h.Handle(event)
194	195		}()
195	196
196	197		select {

@@ -202,7 +203,7 @@ func (bus *InMemory) handleEvent(event domain.Event) {
202	203		Err(err).
203	204		Str("event_id", event.ID).
204	205		Str(zerowrap.FieldEvent, string(event.Type)).
205		-	Str(zerowrap.FieldHandler, fmt.Sprintf("%T", handler)).
	206	+	Str(zerowrap.FieldHandler, fmt.Sprintf("%T", h)).
206	207		Msg("error handling event")
207	208		} else {
208	209		bus.log.Debug().

@@ -210,7 +211,7 @@ func (bus *InMemory) handleEvent(event domain.Event) {
210	211		Str(zerowrap.FieldAdapter, "eventbus").
211	212		Str("event_id", event.ID).
212	213		Str(zerowrap.FieldEvent, string(event.Type)).
213		-	Str(zerowrap.FieldHandler, fmt.Sprintf("%T", handler)).
	214	+	Str(zerowrap.FieldHandler, fmt.Sprintf("%T", h)).
214	215		Dur(zerowrap.FieldDuration, time.Since(start)).
215	216		Msg("event handled successfully")
216	217		}

@@ -220,7 +221,7 @@ func (bus *InMemory) handleEvent(event domain.Event) {
220	221		Str(zerowrap.FieldAdapter, "eventbus").
221	222		Str("event_id", event.ID).
222	223		Str(zerowrap.FieldEvent, string(event.Type)).
223		-	Str(zerowrap.FieldHandler, fmt.Sprintf("%T", handler)).
	224	+	Str(zerowrap.FieldHandler, fmt.Sprintf("%T", h)).
224	225		Dur(zerowrap.FieldDuration, time.Since(start)).
225	226		Msg("handler timeout after 30s")
226	227		}

 	for _, handler := range handlers {
 		if handler.CanHandle(event.Type) {
+			h := handler // shadow loop variable for goroutine capture
 			start := time.Now()
 			done := make(chan error, 1)
 			go func() {
-				done <- handler.Handle(event)
+				done <- h.Handle(event)
 			}()
 			select {
 						Err(err).
 						Str("event_id", event.ID).
 						Str(zerowrap.FieldEvent, string(event.Type)).
-						Str(zerowrap.FieldHandler, fmt.Sprintf("%T", handler)).
+						Str(zerowrap.FieldHandler, fmt.Sprintf("%T", h)).
 						Msg("error handling event")
 				} else {
 					bus.log.Debug().
 						Str(zerowrap.FieldAdapter, "eventbus").
 						Str("event_id", event.ID).
 						Str(zerowrap.FieldEvent, string(event.Type)).
-						Str(zerowrap.FieldHandler, fmt.Sprintf("%T", handler)).
+						Str(zerowrap.FieldHandler, fmt.Sprintf("%T", h)).
 						Dur(zerowrap.FieldDuration, time.Since(start)).
 						Msg("event handled successfully")
 				}
 					Str(zerowrap.FieldAdapter, "eventbus").
 					Str("event_id", event.ID).
 					Str(zerowrap.FieldEvent, string(event.Type)).
-					Str(zerowrap.FieldHandler, fmt.Sprintf("%T", handler)).
+					Str(zerowrap.FieldHandler, fmt.Sprintf("%T", h)).
 					Dur(zerowrap.FieldDuration, time.Since(start)).
 					Msg("handler timeout after 30s")
 			}