A simple test case to measure the additional time taken by defer in golang

defer_test.go

package test

import (
	"sync"
	"testing"
)

type SyncedStruct struct {
	a     int
	mutex sync.RWMutex
}

var (
	item = SyncedStruct{a: 1}
)

func DeferredUnlock() {
	item.mutex.Lock()
	defer item.mutex.Unlock()
	_ = item.a
}

func NotDeferredUnlock() {
	item.mutex.Lock()
	_ = item.a
	item.mutex.Unlock()
}

func BenchmarkDeferredUnlock(t *testing.B) {
	for i := 0; i < t.N; i++ {
		DeferredUnlock()
	}
}

func BenchmarkNotDeferredUnlock(t *testing.B) {
	for i := 0; i < t.N; i++ {
		NotDeferredUnlock()
	}
}