golang benchmark of string concatenation

strings_test.go

package strings

import (
	"bytes"
	"fmt"
	"os"
	"strings"
	"testing"
)

func BenchmarkPrintf(b *testing.B) {
	var err error
	sink, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0666)
	if err != nil {
		b.Fatalf("%s : while opening /dev/null", err)
	}
	for i := 0; i < b.N; i++ {
		_, err = fmt.Fprintf(sink, "%s %s", "first", "second")
		if err != nil {
			b.Fatalf("%s : while writing to /dev/null", err)
		}
	}
	err = sink.Close()
	if err != nil {
		b.Fatalf("%s : while closing /dev/null", err)
	}
}

func BenchmarkConcat(b *testing.B) {
	var err error
	sink, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0666)
	if err != nil {
		b.Fatalf("%s : while opening /dev/null", err)
	}
	for i := 0; i < b.N; i++ {
		var result = "a" + " " + "b"
		_, err = fmt.Fprint(sink, result)
		if err != nil {
			b.Fatalf("%s : while writing to /dev/null", err)
		}
	}
	err = sink.Close()
	if err != nil {
		b.Fatalf("%s : while closing /dev/null", err)
	}
}

func BenchmarkBufferFresh(b *testing.B) {
	var err error
	sink, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0666)
	if err != nil {
		b.Fatalf("%s : while opening dev/null", err)
	}
	for i := 0; i < b.N; i++ {
		buf := bytes.NewBufferString("")
		buf.WriteString("a")
		buf.WriteString(" ")
		buf.WriteString("b")
		_, err = sink.Write(buf.Bytes())
		if err != nil {
			b.Fatalf("%s : while writing to /dev/null", err)
		}
	}
	err = sink.Close()
	if err != nil {
		b.Fatalf("%s : while closing /dev/null", err)
	}
}

func BenchmarkBufferReuse(b *testing.B) {
	var err error
	sink, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0666)
	if err != nil {
		b.Fatalf("%s : while opening dev/null", err)
	}
	buf := bytes.NewBufferString("")
	for i := 0; i < b.N; i++ {
		buf.WriteString("a")
		buf.WriteString(" ")
		buf.WriteString("b")
		_, err = sink.Write(buf.Bytes())
		if err != nil {
			b.Fatalf("%s : while writing to /dev/null", err)
		}
		buf.Truncate(0)
	}
	err = sink.Close()
	if err != nil {
		b.Fatalf("%s : while closing /dev/null", err)
	}
}

func BenchmarkBuilder(b *testing.B) {
	var err error
	sink, err := os.OpenFile(os.DevNull, os.O_WRONLY, 0666)
	if err != nil {
		b.Fatalf("%s : while opening dev/null", err)
	}
	var buf strings.Builder
	for i := 0; i < b.N; i++ {
		buf.WriteString("a")
		buf.WriteString(" ")
		buf.WriteString("b")
		_, err = sink.WriteString(buf.String())
		if err != nil {
			b.Fatalf("%s : while writing to /dev/null", err)
		}
		buf.Reset()
	}
	err = sink.Close()
	if err != nil {
		b.Fatalf("%s : while closing /dev/null", err)
	}
}

/*
[vodolaz095@steel strings]$ go test -bench=. strings_test.go 
goos: linux
goarch: amd64
cpu: Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz
BenchmarkPrintf-8        	 1768626	       675.9 ns/op
BenchmarkConcat-8        	 1760847	       681.7 ns/op
BenchmarkBufferFresh-8   	 1978248	       606.8 ns/op
BenchmarkBufferReuse-8   	 2003402	       601.7 ns/op
BenchmarkBuilder-8       	 1930663	       623.0 ns/op
PASS
ok  	command-line-arguments	9.234s

//*/