Benchmark to compare shared locks vs per-thread locks

lock_test.go

package input

import (
	"fmt"
	"sync"
	"testing"
)

// simple datastruct to provide a lock around an int variable
type Data struct {
	sync.RWMutex
	D int
}

func (d *Data) Get() int {
	d.RLock()
	defer d.RUnlock()
	return d.D
}

func doWork(pb *testing.PB, d *Data) {
	for pb.Next() {
		if d.Get() > 1 {
			fmt.Printf("data is > 1")
		}
	}
}

func BenchmarkSharedLock(b *testing.B) {
	b.SetParallelism(8)
	d := &Data{}
	b.RunParallel(func(pb *testing.PB) {
		doWork(pb, d)
	})
}

func BenchmarkIsolatedLock(b *testing.B) {
	b.SetParallelism(8)
	b.RunParallel(func(pb *testing.PB) {
		d := &Data{}
		doWork(pb, d)
	})
}

anthony:~/go/src/github.com/grafana/metrictank/input$ go test -v -run NONE -bench Lock -cpu=1,2,4
goos: linux
goarch: amd64
pkg: github.com/grafana/metrictank/input
BenchmarkSharedLock             30000000                54.6 ns/op
BenchmarkSharedLock-2           20000000                70.6 ns/op
BenchmarkSharedLock-4           20000000                68.7 ns/op
BenchmarkThreadLock             30000000                56.6 ns/op
BenchmarkThreadLock-2           50000000                27.6 ns/op
BenchmarkThreadLock-4           100000000               14.6 ns/op
PASS
ok      github.com/grafana/metrictank/input     9.283s