英文:
When accessing a public var that's been modified inside a for loop, i cannot see a change
问题
我有一个名为Tpus的公共变量,在一个无限的for循环中修改这个值,但是当我尝试在for循环中打印Tpus和在for循环外的goroutine中打印Tpus时,得到了两个不同的结果。我希望在goroutine中得到与for循环中相同的结果。
var Tpus []string
func TPU_Calc(destination string) {
clusternodes := GetClusterNodes(destination)
go func() {
wg.Add(1)
time.Sleep(2 * time.Second)
for {
time.Sleep(150 * time.Millisecond)
//fmt.Printf("\n + %e", Tpus)
}
}()
for {
slot := GetSlot(destination)
slotleaders := GetSlotLeaders(destination, strconv.FormatUint(slot+10, 10))
for x := 0; x < 80; x++ {
for z := 0; z < len(clusternodes.Result); z++ {
if slotleaders[x] == clusternodes.Result[z].Pubkey {
if len(Tpus) >= 2 {
X := RemoveIndex(Tpus, 0)
Tpus = append(X, clusternodes.Result[x].Tpu)
fmt.Printf("\n + %e", Tpus)
} else {
Tpus = append(Tpus, clusternodes.Result[x].Tpu)
}
}
}
}
}
}
上述代码的结果为:
- [%!e(string=136.144.49.213:8004) %!e(string=198.55.56.164:8004)]
- [%!e(string=198.55.56.164:8004) %!e(string=13.124.174.97:8003)]
- [%!e(string=13.124.174.97:8003) %!e(string=185.16.38.73:8003)]
- [%!e(string=185.16.38.73:8003) %!e(string=103.28.52.250:8003)]
- [%!e(string=103.28.52.250:8003) %!e(string=18.214.103.198:8004)]
- [%!e(string=18.214.103.198:8004) %!e(string=185.188.42.43:9003)]
- [%!e(string=185.188.42.43:9003) %!e(string=135.181.115.253:8003)]
var Tpus []string
func TPU_Calc(destination string) {
clusternodes := GetClusterNodes(destination)
go func() {
wg.Add(1)
time.Sleep(2 * time.Second)
for {
time.Sleep(150 * time.Millisecond)
fmt.Printf("\n + %e", Tpus)
}
}()
for {
slot := GetSlot(destination)
slotleaders := GetSlotLeaders(destination, strconv.FormatUint(slot+10, 10))
for x := 0; x < 80; x++ {
for z := 0; z < len(clusternodes.Result); z++ {
if slotleaders[x] == clusternodes.Result[z].Pubkey {
if len(Tpus) >= 2 {
X := RemoveIndex(Tpus, 0)
Tpus = append(X, clusternodes.Result[x].Tpu)
//fmt.Printf("\n + %e", Tpus)
} else {
Tpus = append(Tpus, clusternodes.Result[x].Tpu)
}
}
}
}
}
}
上述代码的结果为:
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
英文:
I have a public variable which we call Tpus, I modify this value within an infinite for loop, however i get 2 different results when i try to print Tpus in the for loop, and in a goroutine outside the for loop, What im looking to do is get the same result in the goroutine as i get in the for loop.
var Tpus []string
func TPU_Calc(destination string) {
clusternodes := GetClusterNodes(destination)
go func() {
wg.Add(1)
time.Sleep(2 * time.Second)
for {
time.Sleep(150 * time.Millisecond)
//fmt.Printf("\n + %e", Tpus)
}
}()
for {
slot := GetSlot(destination)
slotleaders := GetSlotLeaders(destination, strconv.FormatUint(slot+10, 10))
for x := 0; x < 80; x++ {
for z := 0; z < len(clusternodes.Result); z++ {
if slotleaders[x] == clusternodes.Result[z].Pubkey {
if len(Tpus) >= 2 {
X := RemoveIndex(Tpus, 0)
Tpus = append(X, clusternodes.Result[x].Tpu)
fmt.Printf("\n + %e", Tpus)
} else {
Tpus = append(Tpus, clusternodes.Result[x].Tpu)
}
}
}
}
}
}
Result From Code Above:
- [%!e(string=136.144.49.213:8004) %!e(string=198.55.56.164:8004)]
- [%!e(string=198.55.56.164:8004) %!e(string=13.124.174.97:8003)]
- [%!e(string=13.124.174.97:8003) %!e(string=185.16.38.73:8003)]
- [%!e(string=185.16.38.73:8003) %!e(string=103.28.52.250:8003)]
- [%!e(string=103.28.52.250:8003) %!e(string=18.214.103.198:8004)]
- [%!e(string=18.214.103.198:8004) %!e(string=185.188.42.43:9003)]
- [%!e(string=185.188.42.43:9003) %!e(string=135.181.115.253:8003)]
var Tpus []string
func TPU_Calc(destination string) {
clusternodes := GetClusterNodes(destination)
go func() {
wg.Add(1)
time.Sleep(2 * time.Second)
for {
time.Sleep(150 * time.Millisecond)
fmt.Printf("\n + %e", Tpus)
}
}()
for {
slot := GetSlot(destination)
slotleaders := GetSlotLeaders(destination, strconv.FormatUint(slot+10, 10))
for x := 0; x < 80; x++ {
for z := 0; z < len(clusternodes.Result); z++ {
if slotleaders[x] == clusternodes.Result[z].Pubkey {
if len(Tpus) >= 2 {
X := RemoveIndex(Tpus, 0)
Tpus = append(X, clusternodes.Result[x].Tpu)
//fmt.Printf("\n + %e", Tpus)
} else {
Tpus = append(Tpus, clusternodes.Result[x].Tpu)
}
}
}
}
}
}
Result From Code Above:
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
- [%!e(string=142.132.248.119:8003) %!e(string=3.231.94.117:8004)]
答案1
得分: 1
var globalvar []string
func main() {
var mu sync.Mutex
go func() {
for {
// 阻止对全局变量的访问,以便
// 没有人可以在 goroutine 之外更改它。
// 如果在 goroutine 之外已经锁定,
// 则等待解锁。
mu.Lock()
// 对全局变量进行一些操作...
fmt.Printf("%v\n", globalvar)
// 解锁对全局变量的访问
mu.Unlock()
// 一些代码...
}
}()
for i := 0; i < 255; i++ {
// 阻止对全局变量的访问。
// 如果在 goroutine 内部已经锁定,
// 则等待解锁。
mu.Lock()
// 对全局变量进行一些操作
globalvar = append(globalvar, "Str #"+strconv.Itoa(i))
// 解锁访问
mu.Unlock()
// 一些代码...
}
}
你还可以定义一个带有互斥锁、值和用于更改值的方法的特殊结构。类似这样:
type TpusContainer struct {
mu sync.Mutex
value []string
}
func (t *TpusContainer) RemoveIndex(i int) {
t.mu.Lock()
defer t.mu.Unlock()
t.value = RemoveIndex(t.value, i)
}
func (t *TpusContainer) Append(elem string) {
t.mu.Lock()
defer t.mu.Unlock()
t.value = append(t.value, elem)
}
func (t *TpusContainer) String() string {
t.mu.Lock()
defer t.mu.Unlock()
return fmt.Sprintf("%v", t.value)
}
var Tpus TpusContainer
func main() {
go func() {
for {
fmt.Printf("%v\n", Tpus)
}
}()
for i := 0; i < 255; i++ {
Tpus.RemoveIndex(0)
Tpus.Append("Some string #" + strconv.Itoa(i))
}
}
就个人而言,我更喜欢第二种方法。
英文:
var globalvar []string
func main() {
var mu sync.Mutex
go func() {
for {
// Block access to a global variable, so that
// no one can change it outside the goroutine.
// If it's already locked outside the goroutine,
// then wait for unlocking.
mu.Lock()
// Some actions with a global variable...
fmt.Printf("%v\n", globalvar)
// Unlocking access to a global variable
mu.Unlock()
// Some code...
}
}()
for i := 0; i < 255; i++ {
// Block access to a global variable.
// If it's already locked inside the goroutine,
// then wait for unlocking.
mu.Lock()
// Some actions with a global variable
globalvar = append(globalvar, "Str #"+strconv.Itoa(i))
// Unlock access
mu.Unlock()
// Some code...
}
}
Also you can define a special structure with mutex, value and methods for change it value. Something like this:
type TpusContainer struct {
mu sync.Mutex
value []string
}
func (t *TpusContainer) RemoveIndex(i int) {
t.mu.Lock()
defer t.mu.Unlock()
t.value = RemoveIndex(t.value, i)
}
func (t *TpusContainer) Append(elem string) {
t.mu.Lock()
defer t.mu.Unlock()
t.value = append(t.value, elem)
}
func (t *TpusContainer) String() string {
t.mu.Lock()
defer t.mu.Unlock()
return fmt.Sprintf("%v", t.value)
}
var Tpus TpusContainer
func main() {
go func() {
for {
fmt.Printf("%v\n", Tpus)
}
}()
for i := 0; i < 255; i++ {
Tpus.RemoveIndex(0)
Tpus.Append("Some string #"+strconv.Itoa(i))
}
}
Personally, I prefer the second approach.
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