Benchmarks with 10% syncs versus no syncs.

flushing_test.go

package flushing

import (
	"encoding/binary"
	"fmt"
	"math/rand"
	"os"
	"testing"
)

var MAX uint32 = 1000000

// Write and Reading 0..MAX integers without sync.
func BenchmarkReadWrite(b *testing.B) {

	file, _ := os.OpenFile("log", os.O_RDWR, 0666)

	var i uint32
	for i = 0; i <= MAX; i++ {
		binary.Write(file, binary.LittleEndian, i)
	}

	file.Seek(0, os.SEEK_SET)
	for i = 0; i <= MAX; i = i {
		var n uint32
		binary.Read(file, binary.LittleEndian, &n)
		if n != i {
			panic(fmt.Sprintf("corrupted file; expected %d, was %d", i, n))
		}
		i++
	}

}

// Write and Reading 0..MAX integers with 10% sync.
func BenchmarkReadWriteFlush(b *testing.B) {

	file, _ := os.OpenFile("log", os.O_RDWR, 0666)

	var i uint32
	for i = 0; i <= MAX; i++ {
		binary.Write(file, binary.LittleEndian, i)
		if rand.Float64() < 0.01 {
			file.Sync()
		}
	}

	file.Seek(0, os.SEEK_SET)
	for i = 0; i <= MAX; i++ {
		var n uint32
		binary.Read(file, binary.LittleEndian, &n)
		if n != i {
			panic("corrupted file")
		}
	}

	file.Close()

}

To execute, run it with:

$> go test -c flushing_test.go
$> ./flushing.test -test.bench Bench

The output of a typical run might be:

PASS
BenchmarkReadWrite             1    2062437000 ns/op
BenchmarkReadWriteFlush        1    11519889000 ns/op