Exploring goroutine ordering explicit happen before.

orderExplicitHappenBefore.go

package main
/*
Exploring concept of "Happens Before" using channels to impose order on 
selection of "next" goroutine from runtime scheduling queue.  Trying
to enforce "fairness" whose meaning in this situation guarantees execution
of all goroutines, avoiding goroutine starvation/barging explained
here: https://github.com/golang/go/issues/11506.

go PlayGound: https://play.golang.org/p/4sGKDepzqaV
*/
import (
	"fmt"
	"time"
)

func main() {
	read := make(chan bool)
	term := make(chan bool)
	start := make(chan bool)
	hb := make( chan bool)

	go reader(read, start, term, "1", hb, nil)
	start <-true
	go reader(read, start, term, "2", nil, hb)
	start <-true
	for i := 0; i < 100; i++ {
		// Sleep of 0 
		time.Sleep(0 * time.Nanosecond)
		read <- true
	}
	close(read)
	<-term
	<-term
}
func reader(read chan bool, start chan bool, term chan bool, tag string, hb chan bool, ha chan bool) {
	var tot int
	<-start
	for range read {
		tot++ 
		fmt.Printf("Reader With Start: %s\n", tag)
		if hb != nil { hb <- true}
		if ha != nil { <-ha} 
	}
	fmt.Printf("Reader With Start: %s Total: %d\n", tag, tot)
	term <- true
}