util: fix the issue that memory usage not released after tracker Deta…

…ch (#34592)

ref #34571

util/memory/tracker.go

@@ -217,7 +217,12 @@ func reArrangeFallback(a ActionOnExceed, b ActionOnExceed) ActionOnExceed {
 
 // SetLabel sets the label of a Tracker.
 func (t *Tracker) SetLabel(label int) {
+	parent := t.getParent()
+	t.Detach()
 	t.label = label
+	if parent != nil {
+		t.AttachTo(parent)
+	}
 }
 
 // Label gets the label of a Tracker.
@@ -229,6 +234,10 @@ func (t *Tracker) Label() int {
 // already has a parent, this function will remove it from the old parent.
 // Its consumed memory usage is used to update all its ancestors.
 func (t *Tracker) AttachTo(parent *Tracker) {
+	if parent.isGlobal {
+		t.AttachToGlobalTracker(parent)
+		return
+	}
 	oldParent := t.getParent()
 	if oldParent != nil {
 		oldParent.remove(t)

util/memory/tracker_test.go

@@ -43,6 +43,18 @@ func TestSetLabel(t *testing.T) {
 	require.Equal(t, 0, len(tracker.mu.children))
 }
 
+func TestSetLabel2(t *testing.T) {
+	tracker := NewTracker(1, -1)
+	tracker2 := NewTracker(2, -1)
+	tracker2.AttachTo(tracker)
+	tracker2.Consume(10)
+	require.Equal(t, tracker.BytesConsumed(), int64(10))
+	tracker2.SetLabel(10)
+	require.Equal(t, tracker.BytesConsumed(), int64(10))
+	tracker2.Detach()
+	require.Equal(t, tracker.BytesConsumed(), int64(0))
+}
+
 func TestConsume(t *testing.T) {
 	tracker := NewTracker(1, -1)
 	require.Equal(t, int64(0), tracker.BytesConsumed())