go defer benchmark 1.12 vs 1.13

defer_benchmank.go

package defer_demo

import (
	"testing"
)

func doDefer() int {
	acc := 0
	for i := 0; i < 100; i++ {
		defer func(i int) {
			acc += i
		}(i)
	}
	return acc
}

func noDefer() int {
	acc := 0
	for i := 0; i < 100; i++ {
		func(i int) {
			acc += i
		}(i)
	}
	return acc
}

var blackhole int

func BenchmarkDefer(b *testing.B) {
	s := 1
	for i := 0; i < b.N; i++ {
		s = doDefer()
	}
	blackhole = s
}

var result int

func BenchmarkNoDefer(b *testing.B) {
	s := 1
	for i := 0; i < b.N; i++ {
		s = noDefer()
	}

	result = s
}

result.txt

# go test -v -bench=. -benchmem

go version go1.13 darwin/amd64

BenchmarkDefer-8          255255              4291 ns/op               8 B/op          1 allocs/op
BenchmarkNoDefer-8       9560637               123 ns/op               0 B/op          0 allocs/op


go version go1.12.1 darwin/amd64

BenchmarkDefer-8          300000              4340 ns/op               8 B/op          1 allocs/op
BenchmarkNoDefer-8      10000000               125 ns/op               0 B/op          0 allocs/op

package defer_demo

import (
	"testing"
)

func doDefer() int {
	acc := 0
	defer func(i int) {
		acc += i
	}(1)
	defer func(i int) {
		acc += i
	}(1)
	return acc
}

func noDefer() int {
	acc := 0
	func(i int) {
		acc += i
	}(1)
	func(i int) {
		acc += i
	}(1)
	return acc
}

var blackhole int

func BenchmarkDefer(b *testing.B) {
	s := 1
	for i := 0; i < b.N; i++ {
		s = doDefer()
	}
	blackhole = s
}

var result int

func BenchmarkNoDefer(b *testing.B) {
	s := 1
	for i := 0; i < b.N; i++ {
		s = noDefer()
	}

	result = s
}

1.12

BenchmarkDefer-8        20000000                81.7 ns/op             0 B/op          0 allocs/op
BenchmarkNoDefer-8      2000000000               1.39 ns/op            0 B/op          0 allocs/op

1.13

BenchmarkDefer-8        19694089                57.9 ns/op             0 B/op          0 allocs/op
BenchmarkNoDefer-8      1000000000               1.12 ns/op            0 B/op          0 allocs/op