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golang Map 并发安全的几个点

 2 years ago
source link: http://chen-tao.github.io/2018/01/30/go-sync-map/
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golang Map 并发安全的几个点

发表于 2018-01-30

| 分类于 Golang

有几个坑，需要注意一下
// map_safe.go
// Copyright (C) 2018 chentao <[email protected]>
// Distributed under terms of the MIT license.
package main
import (
"fmt"
"sync"
"time"
type ctr struct {
sync.RWMutex
m map[string]int
func main() {
counter := &ctr{m: make(map[string]int)}
for i := 0; i < 10; i++ {
go bc(counter)
//for i := 0; i < 10; i++ {
// go set(counter, i*10)
//for i := 0; i < 10; i++ {
// go get(counter)
time.Sleep(time.Second * 2)
func bc(counter *ctr) {
for i := 0; i < 10; i++ {
go set(counter, i)
for i := 0; i < 10; i++ {
go get(counter)
// counter 这里必须是引用
func set(counter *ctr, v int) {
counter.Lock()
defer func() {
counter.Unlock()
fmt.Printf("set unlock mutex addr %p \n", &counter.RWMutex)
fmt.Printf("set unlock count addr %p \n", &counter.m)
fmt.Printf("set unlock all addr %p \n", &counter)
//counter.m["some_key"] = v
counter.m["some_key"] = counter.m["some_key"] + v
//time.Sleep(time.Millisecond * 10)
fmt.Println("some_key set:", counter.m["some_key"])
func get(counter *ctr) {
counter.RLock()
defer func() {
counter.RUnlock()
fmt.Printf("get unlock mutex addr %p \n", &counter.RWMutex)
fmt.Printf("get unlock count addr %p \n", &counter.m)
fmt.Printf("get unlock all addr %p \n", &counter)
n := counter.m["some_key"]
fmt.Println("some_key get:", n)
// map_safe.go
// Copyright (C) 2018 chentao <[email protected]>
// Distributed under terms of the MIT license.
package main
import (
"fmt"
"sync"
"time"
"unsafe"
type ctr2 struct {
sync.RWMutex
m map[string]int
func main() {
counter := ctr2{m: make(map[string]int)}
for i := 0; i < 10; i++ {
go counter.bc()
//for i := 0; i < 10; i++ {
// go set(counter, i*10)
//for i := 0; i < 10; i++ {
// go get(counter)
time.Sleep(time.Second * 2)
// counter这里都OK
func (counter *ctr2) bc() {
for i := 0; i < 10; i++ {
go counter.set(i)
for i := 0; i < 10; i++ {
go counter.get()
func (counter *ctr2) set(v int) {
counter.Lock()
defer func() {
counter.Unlock()
fmt.Printf("set unlock mutex addr %p \n", &counter.RWMutex)
fmt.Printf("set unlock count addr %p \n", &counter.m)
fmt.Printf("set unlock all addr %p \n", &(*counter))
fmt.Printf("set unlock all addr %p \n", unsafe.Pointer(counter))
fmt.Printf("set unlock all addr %p \n", counter)
}() // 注意这几个对象引用和地址的区分
//counter.m["some_key"] = v
counter.m["some_key"] = counter.m["some_key"] + v
//time.Sleep(time.Millisecond * 10)
fmt.Println("some_key set:", counter.m["some_key"])
func (counter *ctr2) get() {
counter.RLock()
defer func() {
counter.RUnlock()
fmt.Printf("get unlock mutex addr %p \n", &counter.RWMutex)
fmt.Printf("get unlock count addr %p \n", &counter.m)
fmt.Printf("get unlock all addr %p \n", &(*counter))
fmt.Printf("get unlock all addr %p \n", unsafe.Pointer(counter))
fmt.Printf("get unlock all addr %p \n", counter)
n := counter.m["some_key"]
fmt.Println("some_key get:", n)

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