Signalling concurrent initialisation in Go

signalling_init.go

package main

import (
	"sync"
	"sync/atomic"
	"testing"
)

func BenchmarkClosedChannel(b *testing.B) {
	c := make(chan struct{})
	close(c)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		<-c
	}
}

func BenchmarkWaitGroup(b *testing.B) {
	wg := new(sync.WaitGroup)

	// Imitate a real-world scenario
	// it's used for init signal, so we first start with "uninitialized" state
	wg.Add(1)
	wg.Done()

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		wg.Wait()
	}
}

func BenchmarkAtomicLoad(b *testing.B) {
	const InitializedState = 1

	ap := new(uint64)
	atomic.StoreUint64(ap, InitializedState)

	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		if state := atomic.LoadUint64(ap); state != InitializedState {
			// this can be implemented for example by waiting on a channel close
			panic("wait condition code goes here")
		}
	}
}

signalling_init_results.txt

# 2017 MacBook Pro 15'
# 2,8 GHz Quad-Core Intel Core i7
# Go 1.14.4

BenchmarkClosedChannel
BenchmarkClosedChannel-8   	52708377	        22.2 ns/op
BenchmarkWaitGroup
BenchmarkWaitGroup-8       	364102297	         3.18 ns/op
BenchmarkAtomicLoad
BenchmarkAtomicLoad-8      	1000000000	         0.598 ns/op