fix issue in malloc

Author: mfanjie

examples/module1/struct/main.go

@@ -1,15 +1,22 @@
 package main
 
 import (
+	"encoding/json"
+	"fmt"
 	"reflect"
 )
 
 type MyType struct {
 	Name string `json:"name"`
+	Address
+}
+type Address struct {
+	City string `json:"city"`
 }
-
 func main() {
-	mt := MyType{Name: "test"}
+	mt := MyType{Name: "test",Address: Address{City: "shanghai"}}
+	b, _ := json.Marshal(&mt)
+	fmt.Println(string(b))
 	myType := reflect.TypeOf(mt)
 	name := myType.Field(0)
 	tag := name.Tag.Get("json")

examples/module3/malloc/main.go

@@ -10,10 +10,11 @@ import (
 
 func main() {
 	// only loop 10 times to avoid exhausting the host memory
+	holder := []*C.char{}
 	for i := 1; i <= 10; i++ {
-		// allocMemory malloc and memset 100Mb per time
 		fmt.Printf("Allocating %dMb memory, raw memory is %d\n", i*100, i*100*1024*1025)
-		C.allocMemory()
+		// hold the memory, otherwise it will be freed by GC
+		holder = append(holder, (*C.char)(C.allocMemory()))
 		time.Sleep(time.Minute)
 	}
 }