2 files changed, 59 insertions, 1 deletions
diff --git a/src/internal/singleflight/singleflight.go b/src/internal/singleflight/singleflight.go
index 19d5a94a0b..755bf1c350 100644
--- a/src/internal/singleflight/singleflight.go
+++ b/src/internal/singleflight/singleflight.go
@@ -94,7 +94,9 @@ func (g *Group) doCall(c *call, key string, fn func() (any, error)) {
 	c.wg.Done()
 
 	g.mu.Lock()
-	delete(g.m, key)
+	if g.m[key] == c {
+		delete(g.m, key)
+	}
 	for _, ch := range c.chans {
 		ch <- Result{c.val, c.err, c.dups > 0}
 	}
diff --git a/src/internal/singleflight/singleflight_test.go b/src/internal/singleflight/singleflight_test.go
index 99713c9e14..c8b4a81d52 100644
--- a/src/internal/singleflight/singleflight_test.go
+++ b/src/internal/singleflight/singleflight_test.go
@@ -85,3 +85,59 @@ func TestDoDupSuppress(t *testing.T) {
 		t.Errorf("number of calls = %d; want over 0 and less than %d", got, n)
 	}
 }
+
+func TestForgetUnshared(t *testing.T) {
+	var g Group
+
+	var firstStarted, firstFinished sync.WaitGroup
+
+	firstStarted.Add(1)
+	firstFinished.Add(1)
+
+	key := "key"
+	firstCh := make(chan struct{})
+	go func() {
+		g.Do(key, func() (i interface{}, e error) {
+			firstStarted.Done()
+			<-firstCh
+			firstFinished.Done()
+			return
+		})
+	}()
+
+	firstStarted.Wait()
+	g.ForgetUnshared(key) // from this point no two function using same key should be executed concurrently
+
+	secondCh := make(chan struct{})
+	go func() {
+		g.Do(key, func() (i interface{}, e error) {
+			// Notify that we started
+			secondCh <- struct{}{}
+			<-secondCh
+			return 2, nil
+		})
+	}()
+
+	<-secondCh
+
+	resultCh := g.DoChan(key, func() (i interface{}, e error) {
+		panic("third must not be started")
+	})
+
+	if g.ForgetUnshared(key) {
+		t.Errorf("Before first goroutine finished, key %q is shared, should return false", key)
+	}
+
+	close(firstCh)
+	firstFinished.Wait()
+
+	if g.ForgetUnshared(key) {
+		t.Errorf("After first goroutine finished, key %q is still shared, should return false", key)
+	}
+
+	secondCh <- struct{}{}
+
+	if result := <-resultCh; result.Val != 2 {
+		t.Errorf("We should receive result produced by second call, expected: 2, got %d", result.Val)
+	}
+}