1 files changed, 35 insertions, 0 deletions
diff --git a/src/runtime/metrics_test.go b/src/runtime/metrics_test.go
index cfb09a3..55d7dc4 100644
--- a/src/runtime/metrics_test.go
+++ b/src/runtime/metrics_test.go
@@ -761,3 +761,38 @@ func TestCPUMetricsSleep(t *testing.T) {
 	}
 	t.Errorf(`time.Sleep did not contribute enough to "idle" class: minimum idle time = %.5fs`, minIdleCPUSeconds)
 }
+
+func TestMetricHeapUnusedLargeObjectOverflow(t *testing.T) {
+	// This test makes sure /memory/classes/heap/unused:bytes
+	// doesn't overflow when allocating and deallocating large
+	// objects. It is a regression test for #67019.
+	done := make(chan struct{})
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for {
+			for i := 0; i < 10; i++ {
+				runtime.Escape(make([]byte, 1<<20))
+			}
+			runtime.GC()
+			select {
+			case <-done:
+				return
+			default:
+			}
+		}
+	}()
+	s := []metrics.Sample{
+		{Name: "/memory/classes/heap/unused:bytes"},
+	}
+	for i := 0; i < 1000; i++ {
+		metrics.Read(s)
+		if s[0].Value.Uint64() > 1<<40 {
+			t.Errorf("overflow")
+			break
+		}
+	}
+	done <- struct{}{}
+	wg.Wait()
+}