diff --git a/list/arraylist/arraylist.go b/list/arraylist/arraylist.go
index 859ddda..8b2aa7f 100644
--- a/list/arraylist/arraylist.go
+++ b/list/arraylist/arraylist.go
@@ -70,10 +70,11 @@ func (l *ArrayList) growth() {
 		log.Panic("list size is over listMaxLimit", listMaxLimit)
 	}
 
-	nSize := l.size << 1
+	lcap := uint(len(l.data))
+	nSize := lcap << 1
 	temp := make([]interface{}, nSize, nSize)
 
-	ghidx := l.size / 2
+	ghidx := lcap / 2
 	gtidx := ghidx + l.size + 1
 	copy(temp[ghidx+1:], l.data[l.hidx+1:l.tidx])
 	l.data = temp
@@ -98,7 +99,7 @@ func (l *ArrayList) PushFront(values ...interface{}) {
 
 func (l *ArrayList) PushBack(values ...interface{}) {
 	psize := uint(len(values))
-	for l.tidx+psize > uint(len(l.data)) {
+	for l.tidx+psize > uint(len(l.data)) { // [0 1 2 3 4 5 6]
 		l.growth()
 	}
 
diff --git a/list/arraylist/arraylist_test.go b/list/arraylist/arraylist_test.go
index b8c7ef5..1054b60 100644
--- a/list/arraylist/arraylist_test.go
+++ b/list/arraylist/arraylist_test.go
@@ -1,6 +1,10 @@
 package arraylist
 
 import (
+	"bytes"
+	"encoding/gob"
+	"io/ioutil"
+	"log"
 	"testing"
 
 	"github.com/davecgh/go-spew/spew"
@@ -8,6 +12,7 @@ import (
 
 func TestPush(t *testing.T) {
 	l := New()
+
 	for i := 0; i < 2; i++ {
 		l.PushFront(1)
 	}
@@ -24,6 +29,7 @@ func TestPush(t *testing.T) {
 	if result != "[1 1 2 2]" {
 		t.Error(result)
 	}
+
 }
 
 func TestGrowth(t *testing.T) {
@@ -141,3 +147,25 @@ func TestRemove(t *testing.T) {
 	}
 
 }
+
+func loadTestData() []int {
+	data, err := ioutil.ReadFile("../../l.log")
+	if err != nil {
+		log.Println(err)
+	}
+	var l []int
+	decoder := gob.NewDecoder(bytes.NewReader(data))
+	decoder.Decode(&l)
+	return l
+}
+
+func BenchmarkPush(b *testing.B) {
+	l := loadTestData()
+	b.N = len(l)
+
+	arr := New()
+
+	for i := 0; i < b.N; i++ {
+		arr.PushBack(l[i])
+	}
+}