Benchmark Golang Timers

benchmark_timers.go

package main

import (
	"fmt"
	"sort"
	"sync"
	"testing"
	"time"
)

func TestTimers(t *testing.T) {
	for _, count := range []int{1000, 2000, 5000, 10000, 20000, 50000, 100000, 500000} {
		runTimers(count)
	}
}

func runTimers(count int) {
	durationCh := make(chan time.Duration, count)

	wg := sync.WaitGroup{}
	wg.Add(count)
	for i := 0; i < count; i++ {
		go func() {
			startedAt := time.Now()
			time.AfterFunc(10*time.Millisecond, func() {
				defer wg.Done()
				durationCh <- time.Since(startedAt)
			})
		}()

	}
	wg.Wait()

	close(durationCh)

	durations := []time.Duration{}
	totalDuration := 0 * time.Millisecond
	for duration := range durationCh {
		durations = append(durations, duration)
		totalDuration += duration
	}
	averageDuration := totalDuration / time.Duration(count)
	sort.Slice(durations, func(i, j int) bool {
		return durations[i] < durations[j]
	})

	fmt.Printf("run %v timers with average=%v, pct50=%v, pct99=%v\n", count, averageDuration, durations[count/2], durations[int(float64(count)*0.99)])
}

$ go test ./... -v
=== RUN   TestTimers
run 1000 timers with average=10.367111ms, pct50=10.234219ms, pct99=10.913219ms
run 2000 timers with average=10.431598ms, pct50=10.37367ms, pct99=11.025823ms
run 5000 timers with average=11.873773ms, pct50=11.986249ms, pct99=12.673725ms
run 10000 timers with average=11.954716ms, pct50=12.313613ms, pct99=13.507858ms
run 20000 timers with average=11.456237ms, pct50=10.625529ms, pct99=25.246254ms
run 50000 timers with average=21.223818ms, pct50=14.792982ms, pct99=34.250143ms
run 100000 timers with average=36.010924ms, pct50=31.794761ms, pct99=128.089527ms
run 500000 timers with average=176.676498ms, pct50=138.238588ms, pct99=676.967558ms
--- PASS: TestTimers (1.21s)