*: add initial read benchmark for etcd v3

It includes the initial read benchmark for etcd v3.

This is the first step to give some rough thoughts. I haven't digged
deeper to answer some questions, including why its performance is not
better than HTTP + json, why one put will cause performance downgrade.

Documentation/benchmarks/etcd-3-0-demo-benchmarks.md

@@ -0,0 +1,40 @@
+## Physical machines
+
+GCE n1-highcpu-2 machine type
+
+- 1x dedicated local SSD mounted under /var/lib/etcd
+- 1x dedicated slow disk for the OS
+- 1.8 GB memory
+- 2x CPUs
+- etcd version 2.2.0
+
+## etcd Cluster
+
+1 etcd member running in v3 demo mode
+
+## Testing
+
+Use [etcd v3 benchmark tool](../../hack/v3benchmark/).
+
+## Performance
+
+### reading one single key
+
+| key size in bytes | number of clients | read QPS | 90th Percentile Latency (ms) |
+|-------------------|-------------------|----------|---------------|
+| 256               | 1                 | 2716  | 0.4      |
+| 256               | 64                | 16623 | 6.1      |
+| 256               | 256               | 16622 | 21.7     |
+
+The performance is nearly the same as the one with empty server handler.
+
+### reading one single key after putting
+
+| key size in bytes | number of clients | read QPS | 90th Percentile Latency (ms) |
+|-------------------|-------------------|----------|---------------|
+| 256               | 1                 | 2269  | 0.5      |
+| 256               | 64                | 13582 | 8.6      |
+| 256               | 256               | 13262 | 47.5     |
+
+The performance with empty server handler is not affected by one put. So the
+performance downgrade should be caused by storage package.

tools/v3benchmark/main.go

@@ -0,0 +1,102 @@
+// Copyright 2015 CoreOS, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"flag"
+	"fmt"
+	"os"
+	"sync"
+	"time"
+
+	"github.com/coreos/etcd/Godeps/_workspace/src/golang.org/x/net/context"
+	"github.com/coreos/etcd/Godeps/_workspace/src/google.golang.org/grpc"
+	"github.com/coreos/etcd/etcdserver/etcdserverpb"
+	"github.com/rakyll/pb"
+)
+
+func main() {
+	var c, n int
+	var url string
+	flag.IntVar(&c, "c", 50, "number of connections")
+	flag.IntVar(&n, "n", 200, "number of requests")
+	// TODO: config the number of concurrency in each connection
+	flag.StringVar(&url, "u", "127.0.0.1:12379", "etcd server endpoint")
+	flag.Parse()
+	if flag.NArg() < 1 {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	if act := flag.Args()[0]; act != "get" {
+		fmt.Errorf("unsupported action %v", act)
+		os.Exit(1)
+	}
+	var rangeEnd []byte
+	key := []byte(flag.Args()[1])
+	if len(flag.Args()) > 2 {
+		rangeEnd = []byte(flag.Args()[2])
+	}
+
+	results := make(chan *result, n)
+	bar := pb.New(n)
+	bar.Format("Bom !")
+	bar.Start()
+	start := time.Now()
+	defer func() {
+		bar.Finish()
+		printReport(n, results, time.Now().Sub(start))
+	}()
+
+	var wg sync.WaitGroup
+	wg.Add(c)
+	jobs := make(chan struct{}, n)
+	for i := 0; i < c; i++ {
+		go func() {
+			defer wg.Done()
+
+			conn, err := grpc.Dial(url)
+			if err != nil {
+				fmt.Errorf("dial error: %v", err)
+				os.Exit(1)
+			}
+			etcd := etcdserverpb.NewEtcdClient(conn)
+			req := &etcdserverpb.RangeRequest{Key: key, RangeEnd: rangeEnd}
+
+			for _ = range jobs {
+				st := time.Now()
+				resp, err := etcd.Range(context.Background(), req)
+
+				var errStr string
+				if err != nil {
+					errStr = err.Error()
+				} else {
+					errStr = resp.Header.Error
+				}
+				results <- &result{
+					errStr:   errStr,
+					duration: time.Now().Sub(st),
+				}
+				bar.Increment()
+			}
+		}()
+	}
+	for i := 0; i < n; i++ {
+		jobs <- struct{}{}
+	}
+	close(jobs)
+
+	wg.Wait()
+}

tools/v3benchmark/report.go

@@ -0,0 +1,156 @@
+// Copyright 2014 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// the file is borrowed from github.com/rakyll/boom/boomer/print.go
+
+package main
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+	"time"
+)
+
+const (
+	barChar = "∎"
+)
+
+type result struct {
+	errStr   string
+	duration time.Duration
+}
+
+type report struct {
+	avgTotal float64
+	fastest  float64
+	slowest  float64
+	average  float64
+	rps      float64
+
+	results chan *result
+	total   time.Duration
+
+	errorDist map[string]int
+	lats      []float64
+}
+
+func printReport(size int, results chan *result, total time.Duration) {
+	r := &report{
+		results:   results,
+		total:     total,
+		errorDist: make(map[string]int),
+	}
+	r.finalize()
+}
+
+func (r *report) finalize() {
+	for {
+		select {
+		case res := <-r.results:
+			if res.errStr != "" {
+				r.errorDist[res.errStr]++
+			} else {
+				r.lats = append(r.lats, res.duration.Seconds())
+				r.avgTotal += res.duration.Seconds()
+			}
+		default:
+			r.rps = float64(len(r.lats)) / r.total.Seconds()
+			r.average = r.avgTotal / float64(len(r.lats))
+			r.print()
+			return
+		}
+	}
+}
+
+func (r *report) print() {
+	sort.Float64s(r.lats)
+
+	if len(r.lats) > 0 {
+		r.fastest = r.lats[0]
+		r.slowest = r.lats[len(r.lats)-1]
+		fmt.Printf("\nSummary:\n")
+		fmt.Printf("  Total:\t%4.4f secs.\n", r.total.Seconds())
+		fmt.Printf("  Slowest:\t%4.4f secs.\n", r.slowest)
+		fmt.Printf("  Fastest:\t%4.4f secs.\n", r.fastest)
+		fmt.Printf("  Average:\t%4.4f secs.\n", r.average)
+		fmt.Printf("  Requests/sec:\t%4.4f\n", r.rps)
+		r.printHistogram()
+		r.printLatencies()
+	}
+
+	if len(r.errorDist) > 0 {
+		r.printErrors()
+	}
+}
+
+// Prints percentile latencies.
+func (r *report) printLatencies() {
+	pctls := []int{10, 25, 50, 75, 90, 95, 99}
+	data := make([]float64, len(pctls))
+	j := 0
+	for i := 0; i < len(r.lats) && j < len(pctls); i++ {
+		current := i * 100 / len(r.lats)
+		if current >= pctls[j] {
+			data[j] = r.lats[i]
+			j++
+		}
+	}
+	fmt.Printf("\nLatency distribution:\n")
+	for i := 0; i < len(pctls); i++ {
+		if data[i] > 0 {
+			fmt.Printf("  %v%% in %4.4f secs.\n", pctls[i], data[i])
+		}
+	}
+}
+
+func (r *report) printHistogram() {
+	bc := 10
+	buckets := make([]float64, bc+1)
+	counts := make([]int, bc+1)
+	bs := (r.slowest - r.fastest) / float64(bc)
+	for i := 0; i < bc; i++ {
+		buckets[i] = r.fastest + bs*float64(i)
+	}
+	buckets[bc] = r.slowest
+	var bi int
+	var max int
+	for i := 0; i < len(r.lats); {
+		if r.lats[i] <= buckets[bi] {
+			i++
+			counts[bi]++
+			if max < counts[bi] {
+				max = counts[bi]
+			}
+		} else if bi < len(buckets)-1 {
+			bi++
+		}
+	}
+	fmt.Printf("\nResponse time histogram:\n")
+	for i := 0; i < len(buckets); i++ {
+		// Normalize bar lengths.
+		var barLen int
+		if max > 0 {
+			barLen = counts[i] * 40 / max
+		}
+		fmt.Printf("  %4.3f [%v]\t|%v\n", buckets[i], counts[i], strings.Repeat(barChar, barLen))
+	}
+}
+
+func (r *report) printErrors() {
+	fmt.Printf("\nError distribution:\n")
+	for err, num := range r.errorDist {
+		fmt.Printf("  [%d]\t%s\n", num, err)
+	}
+}