Race of golang

because golang Medium go It's very convenient , Plus functions are very easy to hide go.
So a lot of times , When we write a program , We don't know if this program will have any problems in the case of concurrency .

So in essence ,goroutine The use of increases the risk factor of the function . For example, a Global or public variables , If it is not locked , Let's write down a relatively large project , I don't know if this variable will Cause multiple goroutine competition .

Take a look at the following example , Think about val Whether the variable needs to be locked ？

package main
 
import(
    "fmt"
    "time"
)
 
func main() {
    
    val := 1
    go func(){
    
        val = 2
    }()
    val = 3
    fmt.Println("val:",val)
 
    for{
    
        time.Sleep(time.Second)
    }
}

result ：

This command outputs Warning, Tell us ,goroutine7 Run to the The first 110 That's ok and main goroutine Run to the The first 112 That's ok It's time to trigger the competition .
and goroutine7 Is in The first 109 That's ok When it comes to .

Conclusion ：go run - race *.go The command can help you check your code for missing locks , Competitive detection .