From 17c6e90cd58d4eef0f6cad2f772bb978b21b163f Mon Sep 17 00:00:00 2001
From: lyuxuan <yuxuanli@google.com>
Date: Tue, 2 Jan 2018 10:46:13 -0800
Subject: [PATCH] compare atomic and mutex performance for incrementing/storing
 one variable (#1757)

---
 benchmark/primitives/primitives_test.go | 143 +++++++++++++++++++++++-
 1 file changed, 142 insertions(+), 1 deletion(-)

diff --git a/benchmark/primitives/primitives_test.go b/benchmark/primitives/primitives_test.go
index 59355590..9937ae77 100644
--- a/benchmark/primitives/primitives_test.go
+++ b/benchmark/primitives/primitives_test.go
@@ -1,3 +1,5 @@
+// +build go1.7
+
 /*
  *
  * Copyright 2017 gRPC authors.
@@ -21,9 +23,12 @@
 package primitives_test
 
 import (
+	"fmt"
 	"sync"
 	"sync/atomic"
 	"testing"
+	"time"
+	"unsafe"
 )
 
 func BenchmarkSelectClosed(b *testing.B) {
@@ -76,7 +81,7 @@ func BenchmarkAtomicBool(b *testing.B) {
 	}
 }
 
-func BenchmarkAtomicValue(b *testing.B) {
+func BenchmarkAtomicValueLoad(b *testing.B) {
 	c := atomic.Value{}
 	c.Store(0)
 	x := 0
@@ -92,6 +97,16 @@ func BenchmarkAtomicValue(b *testing.B) {
 	}
 }
 
+func BenchmarkAtomicValueStore(b *testing.B) {
+	c := atomic.Value{}
+	v := 123
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c.Store(v)
+	}
+	b.StopTimer()
+}
+
 func BenchmarkMutex(b *testing.B) {
 	c := sync.Mutex{}
 	x := 0
@@ -188,6 +203,132 @@ func BenchmarkMutexWithoutDefer(b *testing.B) {
 	}
 }
 
+func BenchmarkAtomicAddInt64(b *testing.B) {
+	var c int64
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		atomic.AddInt64(&c, 1)
+	}
+	b.StopTimer()
+	if c != int64(b.N) {
+		b.Fatal("error")
+	}
+}
+
+func BenchmarkAtomicTimeValueStore(b *testing.B) {
+	var c atomic.Value
+	t := time.Now()
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c.Store(t)
+	}
+	b.StopTimer()
+}
+
+func BenchmarkAtomic16BValueStore(b *testing.B) {
+	var c atomic.Value
+	t := struct {
+		a int64
+		b int64
+	}{
+		123, 123,
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c.Store(t)
+	}
+	b.StopTimer()
+}
+
+func BenchmarkAtomic32BValueStore(b *testing.B) {
+	var c atomic.Value
+	t := struct {
+		a int64
+		b int64
+		c int64
+		d int64
+	}{
+		123, 123, 123, 123,
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		c.Store(t)
+	}
+	b.StopTimer()
+}
+
+func BenchmarkAtomicPointerStore(b *testing.B) {
+	t := 123
+	var up unsafe.Pointer
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		atomic.StorePointer(&up, unsafe.Pointer(&t))
+	}
+	b.StopTimer()
+}
+
+func BenchmarkAtomicTimePointerStore(b *testing.B) {
+	t := time.Now()
+	var up unsafe.Pointer
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		atomic.StorePointer(&up, unsafe.Pointer(&t))
+	}
+	b.StopTimer()
+}
+
+func BenchmarkValueStoreWithContention(b *testing.B) {
+	t := 123
+	for _, n := range []int{10, 100, 1000, 10000, 100000} {
+		b.Run(fmt.Sprintf("Atomic/%v", n), func(b *testing.B) {
+			var wg sync.WaitGroup
+			var c atomic.Value
+			for i := 0; i < n; i++ {
+				wg.Add(1)
+				go func() {
+					for j := 0; j < b.N; j++ {
+						c.Store(t)
+					}
+					wg.Done()
+				}()
+			}
+			wg.Wait()
+		})
+		b.Run(fmt.Sprintf("AtomicStorePointer/%v", n), func(b *testing.B) {
+			var wg sync.WaitGroup
+			var up unsafe.Pointer
+			for i := 0; i < n; i++ {
+				wg.Add(1)
+				go func() {
+					for j := 0; j < b.N; j++ {
+						atomic.StorePointer(&up, unsafe.Pointer(&t))
+					}
+					wg.Done()
+				}()
+			}
+			wg.Wait()
+		})
+		b.Run(fmt.Sprintf("Mutex/%v", n), func(b *testing.B) {
+			var wg sync.WaitGroup
+			var c int
+			mu := sync.Mutex{}
+			for i := 0; i < n; i++ {
+				wg.Add(1)
+				go func() {
+					for j := 0; j < b.N; j++ {
+						mu.Lock()
+						c = t
+						mu.Unlock()
+					}
+					wg.Done()
+				}()
+			}
+			_ = c
+			wg.Wait()
+		})
+	}
+}
+
 type myFooer struct{}
 
 func (myFooer) Foo() {}