diff --git a/.gitignore b/.gitignore
index c8d4bef..287fa1a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -20,4 +20,5 @@
 
 # Go workspace file
 go.work
-*.prof
\ No newline at end of file
+*.prof
+example
\ No newline at end of file
diff --git a/cmd/example.go b/cmd/example.go
index 5873bb5..686116a 100644
--- a/cmd/example.go
+++ b/cmd/example.go
@@ -3,13 +3,15 @@ package main
 import (
 	"context"
 	"fmt"
+	"log"
+	"os"
 	"runtime"
 
 	gotaskflow "github.com/noneback/go-taskflow"
 )
 
 func main() {
-	executor := gotaskflow.NewExecutor(uint(runtime.NumCPU()))
+	executor := gotaskflow.NewExecutor(uint(runtime.NumCPU() - 1))
 	tf := gotaskflow.NewTaskFlow("G")
 	A, B, C :=
 		gotaskflow.NewTask("A", func(ctx *context.Context) {
@@ -38,8 +40,51 @@ func main() {
 	C.Succeed(A1)
 	C.Succeed(B1)
 
-	tf.Push(A, B, C)
-	tf.Push(A1, B1, C1)
+	subflow := gotaskflow.NewSubflow("sub1", func(sf *gotaskflow.Subflow) {
+		A2, B2, C2 :=
+			gotaskflow.NewTask("A2", func(ctx *context.Context) {
+				fmt.Println("A2")
+			}),
+			gotaskflow.NewTask("B2", func(ctx *context.Context) {
+				fmt.Println("B2")
+			}),
+			gotaskflow.NewTask("C2", func(ctx *context.Context) {
+				fmt.Println("C2")
+			})
+		A2.Precede(B2)
+		C2.Precede(B2)
+		sf.Push(A2, B2, C2)
+	})
+
+	subflow2 := gotaskflow.NewSubflow("sub2", func(sf *gotaskflow.Subflow) {
+		A3, B3, C3 :=
+			gotaskflow.NewTask("A3", func(ctx *context.Context) {
+				fmt.Println("A3")
+			}),
+			gotaskflow.NewTask("B3", func(ctx *context.Context) {
+				fmt.Println("B3")
+			}),
+			gotaskflow.NewTask("C3", func(ctx *context.Context) {
+				fmt.Println("C3")
+				// time.Sleep(10 * time.Second)
+			})
+		A3.Precede(B3)
+		C3.Precede(B3)
+		sf.Push(A3, B3, C3)
+	})
 
+	subflow.Precede(B)
+	subflow.Precede(subflow2)
+
+	tf.Push(A, B, C)
+	tf.Push(A1, B1, C1, subflow, subflow2)
 	executor.Run(tf).Wait()
+	fmt.Println("Print DOT")
+	if err := gotaskflow.Visualizer.Visualize(tf, os.Stdout); err != nil {
+		log.Fatal(err)
+	}
+	fmt.Println("Print Flamegraph")
+	if err := executor.Profile(os.Stdout); err != nil {
+		log.Fatal(err)
+	}
 }
diff --git a/readme.md b/readme.md
index dcb728a..585ac83 100644
--- a/readme.md
+++ b/readme.md
@@ -35,7 +35,7 @@ import (
 )
 
 func main() {
-	executor := gotaskflow.NewExecutor(runtime.NumCPU() - 1)
+	executor := gotaskflow.NewExecutor(uint(runtime.NumCPU() - 1))
 	tf := gotaskflow.NewTaskFlow("G")
 	A, B, C :=
 		gotaskflow.NewTask("A", func(ctx *context.Context) {
@@ -100,19 +100,19 @@ func main() {
 	subflow.Precede(B)
 	subflow.Precede(subflow2)
 
-	tf := gotaskflow.NewTaskFlow("G")
 	tf.Push(A, B, C)
 	tf.Push(A1, B1, C1, subflow, subflow2)
-	exector.Run(tf).Wait()
+	executor.Run(tf).Wait()
 	fmt.Println("Print DOT")
 	if err := gotaskflow.Visualizer.Visualize(tf, os.Stdout); err != nil {
 		log.Fatal(err)
 	}
 	fmt.Println("Print Flamegraph")
-	if err :=exector.Profile(os.Stdout);err != nil {
+	if err := executor.Profile(os.Stdout); err != nil {
 		log.Fatal(err)
 	}
 }
+
 ```
 ### How to use visualize taskflow
 ```go