diff --git a/container/gqueue/gqueue.go b/container/gqueue/gqueue.go
index 67f9593f87d..5923db1b43b 100644
--- a/container/gqueue/gqueue.go
+++ b/container/gqueue/gqueue.go
@@ -27,7 +27,6 @@ import (
 // Queue is a concurrent-safe queue built on doubly linked list and channel.
 type Queue struct {
 	limit  int              // Limit for queue size.
-	length *gtype.Int64     // Queue length.
 	list   *glist.List      // Underlying list structure for data maintaining.
 	closed *gtype.Bool      // Whether queue is closed.
 	events chan struct{}    // Events for data writing.
@@ -45,7 +44,6 @@ const (
 func New(limit ...int) *Queue {
 	q := &Queue{
 		closed: gtype.NewBool(),
-		length: gtype.NewInt64(),
 	}
 	if len(limit) > 0 && limit[0] > 0 {
 		q.limit = limit[0]
@@ -62,7 +60,6 @@ func New(limit ...int) *Queue {
 // Push pushes the data `v` into the queue.
 // Note that it would panic if Push is called after the queue is closed.
 func (q *Queue) Push(v interface{}) {
-	q.length.Add(1)
 	if q.limit > 0 {
 		q.C <- v
 	} else {
@@ -76,9 +73,7 @@ func (q *Queue) Push(v interface{}) {
 // Pop pops an item from the queue in FIFO way.
 // Note that it would return nil immediately if Pop is called after the queue is closed.
 func (q *Queue) Pop() interface{} {
-	item := <-q.C
-	q.length.Add(-1)
-	return item
+	return <-q.C
 }
 
 // Close closes the queue.
@@ -101,13 +96,18 @@ func (q *Queue) Close() {
 }
 
 // Len returns the length of the queue.
-// Note that the result might not be accurate as there's an
+// Note that the result might not be accurate if using unlimited queue size as there's an
 // asynchronous channel reading the list constantly.
 func (q *Queue) Len() (length int64) {
-	return q.length.Val()
+	bufferedSize := int64(len(q.C))
+	if q.limit > 0 {
+		return bufferedSize
+	}
+	return int64(q.list.Size()) + bufferedSize
 }
 
 // Size is alias of Len.
+// Deprecated: use Len instead.
 func (q *Queue) Size() int64 {
 	return q.Len()
 }
@@ -123,14 +123,11 @@ func (q *Queue) asyncLoopFromListToChannel() {
 	for !q.closed.Val() {
 		<-q.events
 		for !q.closed.Val() {
-			if length := q.list.Len(); length > 0 {
-				if length > defaultBatchSize {
-					length = defaultBatchSize
-				}
-				for _, v := range q.list.PopFronts(length) {
-					// When q.C is closed, it will panic here, especially q.C is being blocked for writing.
-					// If any error occurs here, it will be caught by recover and be ignored.
-					q.C <- v
+			if bufferLength := q.list.Len(); bufferLength > 0 {
+				// When q.C is closed, it will panic here, especially q.C is being blocked for writing.
+				// If any error occurs here, it will be caught by recover and be ignored.
+				for i := 0; i < bufferLength; i++ {
+					q.C <- q.list.PopFront()
 				}
 			} else {
 				break
diff --git a/container/gqueue/gqueue_z_unit_test.go b/container/gqueue/gqueue_z_unit_test.go
index fb171d4cc7e..9fee57afc36 100644
--- a/container/gqueue/gqueue_z_unit_test.go
+++ b/container/gqueue/gqueue_z_unit_test.go
@@ -18,14 +18,31 @@ import (
 
 func TestQueue_Len(t *testing.T) {
 	gtest.C(t, func(t *gtest.T) {
-		max := 100
-		for n := 10; n < max; n++ {
-			q1 := gqueue.New(max)
-			for i := 0; i < max; i++ {
+		var (
+			maxNum   = 100
+			maxTries = 100
+		)
+		for n := 10; n < maxTries; n++ {
+			q1 := gqueue.New(maxNum)
+			for i := 0; i < maxNum; i++ {
 				q1.Push(i)
 			}
-			t.Assert(q1.Len(), max)
-			t.Assert(q1.Size(), max)
+			t.Assert(q1.Len(), maxNum)
+			t.Assert(q1.Size(), maxNum)
+		}
+	})
+	gtest.C(t, func(t *gtest.T) {
+		var (
+			maxNum   = 100
+			maxTries = 100
+		)
+		for n := 10; n < maxTries; n++ {
+			q1 := gqueue.New()
+			for i := 0; i < maxNum; i++ {
+				q1.Push(i)
+			}
+			t.AssertLE(q1.Len(), maxNum)
+			t.AssertLE(q1.Size(), maxNum)
 		}
 	})
 }
@@ -71,3 +88,19 @@ func TestQueue_Close(t *testing.T) {
 		q1.Close()
 	})
 }
+
+func Test_Issue2509(t *testing.T) {
+	gtest.C(t, func(t *gtest.T) {
+		q := gqueue.New()
+		q.Push(1)
+		q.Push(2)
+		q.Push(3)
+		t.Assert(q.Len(), 3)
+		t.Assert(<-q.C, 1)
+		t.Assert(q.Len(), 2)
+		t.Assert(<-q.C, 2)
+		t.Assert(q.Len(), 1)
+		t.Assert(<-q.C, 3)
+		t.Assert(q.Len(), 0)
+	})
+}