goroutines.go

package main

import (
	"fmt"
	"runtime"
	"time"
)

func waitAround(die chan bool) {
	<- die
}

func main() {
	cpus := runtime.NumCPU()
	runtime.GOMAXPROCS(cpus)

	count := 100000

	die := make(chan bool)

	var startMemory runtime.MemStats
	runtime.ReadMemStats(&startMemory)

	start := time.Now()
	for i := 0; i < count; i++ {
		go waitAround(die)
	}
	elapsed := time.Since(start)

	var endMemory runtime.MemStats
	runtime.ReadMemStats(&endMemory)

	fmt.Printf("Started %d goroutines on %d CPUs in %f seconds\n",
		count, cpus, elapsed.Seconds())
	fmt.Printf("Memory before %d, memory after %d\n", startMemory.Alloc,
		endMemory.Alloc)
	fmt.Printf("%d goroutines running\n", runtime.NumGoroutine())

	close(die)
}