diff --git a/.gitignore b/.gitignore
index 66fd13c..1c2d52b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,15 +1 @@
-# Binaries for programs and plugins
-*.exe
-*.exe~
-*.dll
-*.so
-*.dylib
-
-# Test binary, built with `go test -c`
-*.test
-
-# Output of the go coverage tool, specifically when used with LiteIDE
-*.out
-
-# Dependency directories (remove the comment below to include it)
-# vendor/
+.idea/*
diff --git a/README.md b/README.md
index 2c91684..6543de3 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,31 @@
 # gls
 goroutine local storage
+
+# demo
+```
+package main
+
+import (
+	"fmt"
+	"github.com/go-basic/gls"
+	"sync"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func(idx int) {
+			defer wg.Done()
+			defer gls.Clean()
+
+			defer func() {
+				fmt.Printf("%d: number = %d\n", idx, gls.Get("number"))
+			}()
+			gls.Set("number", idx+100)
+		}(i)
+	}
+	wg.Wait()
+}
+
+```
diff --git a/examples/main.go b/examples/main.go
new file mode 100644
index 0000000..180098c
--- /dev/null
+++ b/examples/main.go
@@ -0,0 +1,24 @@
+package main
+
+import (
+	"fmt"
+	"github.com/go-basic/gls"
+	"sync"
+)
+
+func main() {
+	var wg sync.WaitGroup
+	for i := 0; i < 5; i++ {
+		wg.Add(1)
+		go func(idx int) {
+			defer wg.Done()
+			defer gls.Clean()
+
+			defer func() {
+				fmt.Printf("%d: number = %d\n", idx, gls.Get("number"))
+			}()
+			gls.Set("number", idx+100)
+		}(i)
+	}
+	wg.Wait()
+}
diff --git a/gls.go b/gls.go
new file mode 100644
index 0000000..b57a3ab
--- /dev/null
+++ b/gls.go
@@ -0,0 +1,55 @@
+package gls
+
+import (
+	"fmt"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+)
+
+var gls struct {
+	m map[int64]map[interface{}]interface{}
+	sync.RWMutex
+}
+
+func init() {
+	gls.m = make(map[int64]map[interface{}]interface{})
+}
+
+func GetGoId() int64 {
+	var (
+		buf [64]byte
+		n   = runtime.Stack(buf[:], false)
+		stk = strings.TrimPrefix(string(buf[:n]), "goroutine ")
+	)
+	idField := strings.Fields(stk)[0]
+	id, err := strconv.Atoi(idField)
+	if err != nil {
+		panic(fmt.Errorf("can not get goroutine id: %v", err))
+	}
+	return int64(id)
+}
+
+func Get(key interface{}) interface{} {
+	gls.RLock()
+	defer gls.RUnlock()
+	goId := GetGoId()
+	return gls.m[goId][key]
+}
+
+func Set(key interface{}, v interface{}) {
+	gls.Lock()
+	defer gls.Unlock()
+	goId := GetGoId()
+	if _, ok := gls.m[goId][key]; !ok {
+		gls.m[goId] = make(map[interface{}]interface{})
+	}
+	gls.m[goId][key] = v
+}
+
+func Clean() {
+	gls.Lock()
+	defer gls.Unlock()
+	delete(gls.m, GetGoId())
+}
diff --git a/gls_test.go b/gls_test.go
new file mode 100644
index 0000000..844be66
--- /dev/null
+++ b/gls_test.go
@@ -0,0 +1,51 @@
+package gls
+
+import (
+	"fmt"
+	"strconv"
+	"testing"
+)
+
+var key = "test"
+
+func GO(fn func()) {
+	go fn()
+}
+
+func TestGls(t *testing.T) {
+	GO(func() {
+		defer Clean()
+		Set(key, "aaa")
+		testPrint()
+	})
+	GO(func() {
+		defer Clean()
+		Set(key, "bbb")
+		testPrint()
+	})
+	GO(func() {
+		defer Clean()
+		Set(key, "ccc")
+		testPrint()
+	})
+}
+
+
+func BenchmarkGls(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		GO(func() {
+			defer Clean()
+			Set(key, "ccc"+strconv.FormatInt(GetGoId(), 10))
+			testGet()
+		})
+	}
+}
+
+func testPrint() {
+	fmt.Println(Get(key), GetGoId())
+}
+
+func testGet() {
+	Get(key)
+}
+
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..27b605b
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module github.com/go-basic/gls
+
+go 1.15