fmt.go例程中的打印*主线程循环时可能不会输出

Question

The following code as is in https://play.golang.org/p/X1-jZ2JcbOQ

package main
import (
        "fmt"
)
func p(s string) {
        fmt.Println(s)
}

func main() {
    go fmt.Println("1")
    go p("2")
    for {}   // infinite loop
}

prints 1 2 definitely in Windows with golang 1.11 but prints nothing definitely in Linux with golang 1.11.4. I can understand the former behavior but not the latter. Why is the go program not running non-master thread all the time?

Is there a reason behind this?

Answer 1

The Go Playground runs with GOMAXPROCS=1. Try this on the playground:

package main

import (
  "fmt"
  "runtime"
)

func main() {
  fmt.Println(runtime.GOMAXPROCS(0))
}

When you are running locally, you would perhaps have higher value of GOMAXPROCS.

Even on playground, you can see the printing work if you deschedule the main goroutine as below by introducing a Sleep [https://play.golang.org/p/QquMPZSd6kI]:

func main() {
    go fmt.Println("1")
    go p("2")

    time.Sleep(time.Second)
    for {}
 }

OR

Change the GOMAXPROCS at start:

    runtime.GOMAXPROCS(2)