Go lang：在不同进程上运行例程

Question

I want to run a 3 go routine on different process. Upon research I found that I need to use runtime.GOMAXPROCS(). But even after using runtime.GOMAXPROCS(), all routine runs on same process. How can I make it run on different process. Below is the code and output. Here is the link to goplayground

func main() {

    runtime.GOMAXPROCS(4)

    fmt.Printf("Number of CPU %d 
",runtime.NumCPU())

    fmt.Printf("Process id of main %d 

",os.Getpid())


    for i:=0 ;i<3; i++{
        go printAndSleep(i)
    }

    time.Sleep(time.Second * 100)

}

func printAndSleep(i int){
    for {
        fmt.Printf("Process id of %d go routine %d 
",i,os.Getpid())
        time.Sleep(time.Second * 2)
    }   
}

Output :

Number of CPU 8 
Process id of main 16874 

Process id of 0 go routine 16874 
Process id of 2 go routine 16874 
Process id of 1 go routine 16874 
Process id of 0 go routine 16874 
Process id of 1 go routine 16874 
Process id of 2 go routine 16874 
Process id of 0 go routine 16874 
Process id of 1 go routine 16874 
Process id of 2 go routine 16874 
Process id of 2 go routine 16874 
Process id of 0 go routine 16874 
Process id of 1 go routine 16874 

Here you can see all the routine runs on same process even though I have used GOMAXPROCS . Why is that? Am I using it wrong

Answer 1

If you want only one goroutine running on each process, you can use runtime.LockOSThread() to make a 1:1 relation between process and goroutines running on that process. In your case, you should invoke runtime.LockOSThread every time you launch a new goroutine.

for i:=0 ;i<3; i++{
    go func(){
        runtime.LockOSThread()
        printAndSleep(i)
    }()
}