metrics: Add Throughput to Metrics (#420)

* echosrv: Add sleep flag

* metrics: Add Throughput to Metrics

This commit adds a `Throughput` field to the `Metrics` struct which
represents the rate of successful requests per second. It is calculated
by dividing the number of successful requests by the time span in
seconds starting from the beginning of the earliest request in the
result set and ending in the time the very last response arrived.

README.md

@@ -380,7 +380,7 @@ Examples:
 #### `report -type=text`
 
 ```console
-Requests      [total, rate]             1200, 120.00
+Requests      [total, rate, throughput] 1200, 120.00, 65.87
 Duration      [total, attack, wait]     10.094965987s, 9.949883921s, 145.082066ms
 Latencies     [mean, 50, 95, 99, max]   113.172398ms, 108.272568ms, 140.18235ms, 247.771566ms, 264.815246ms
 Bytes In      [total, mean]             3714690, 3095.57
@@ -399,7 +399,8 @@ Get http://localhost:6060: http: can't write HTTP request on broken connection
 The `Requests` row shows:
 
 - The `total` number of issued requests.
-- The real request `rate` sustained during the attack.
+- The real request `rate` sustained during the `attack` period.
+- The `throughput` of successful requests over the `total` period.
 
 The `Duration` row shows:
 
@@ -452,6 +453,7 @@ The `Error Set` shows a unique set of errors returned by all issued requests. Th
   "wait": 3507222,
   "requests": 100,
   "rate": 101.01010672380401,
+  "throughput": 101.00012489812,
   "success": 1,
   "status_codes": {
     "200": 100
@@ -693,14 +695,7 @@ The `report` command accepts multiple result files.
 It'll read and sort them by timestamp before generating reports.
 
 ```console
-$ vegeta report 10.0.1.1.bin 10.0.2.1.bin 10.0.3.1.bin
-Requests      [total, rate]         3600000, 60000.00
-Latencies     [mean, 95, 99, max]   223.340085ms, 326.913687ms, 416.537743ms, 7.788103259s
-Bytes In      [total, mean]         3714690, 3095.57
-Bytes Out     [total, mean]         0, 0.00
-Success       [ratio]               100.0%
-Status Codes  [code:count]          200:3600000
-Error Set:
+vegeta report *.bin
 ```
 
 ## Usage: Real-time Analysis

internal/cmd/echosrv/main.go

@@ -1,15 +1,19 @@
 package main
 
 import (
+	"flag"
 	"log"
 	"net/http"
 	"net/http/httputil"
-	"os"
 	"sync/atomic"
 	"time"
 )
 
 func main() {
+	sleep := flag.Duration("sleep", 0, "Time to sleep per request")
+
+	flag.Parse()
+
 	count := uint64(0)
 	go func(last time.Time) {
 		ticks := time.Tick(time.Second)
@@ -20,8 +24,10 @@ func main() {
 		}
 	}(time.Now())
 
-	http.ListenAndServe(os.Args[1], http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		atomic.AddUint64(&count, 1)
+	http.ListenAndServe(flag.Arg(0), http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		defer atomic.AddUint64(&count, 1)
+		time.Sleep(*sleep)
+
 		bs, _ := httputil.DumpRequest(r, true)
 		w.Write(bs)
 	}))

lib/metrics.go

@@ -18,7 +18,7 @@ type Metrics struct {
 	BytesIn ByteMetrics `json:"bytes_in"`
 	// BytesOut holds computed outgoing byte metrics.
 	BytesOut ByteMetrics `json:"bytes_out"`
-	// First is the earliest timestamp in a Result set.
+	// Earliest is the earliest timestamp in a Result set.
 	Earliest time.Time `json:"earliest"`
 	// Latest is the latest timestamp in a Result set.
 	Latest time.Time `json:"latest"`
@@ -30,8 +30,10 @@ type Metrics struct {
 	Wait time.Duration `json:"wait"`
 	// Requests is the total number of requests executed.
 	Requests uint64 `json:"requests"`
-	// Rate is the rate of requests per second.
+	// Rate is the rate of sent requests per second.
 	Rate float64 `json:"rate"`
+	// Throughput is the rate of successful requests per second.
+	Throughput float64 `json:"throughput"`
 	// Success is the percentage of non-error responses.
 	Success float64 `json:"success"`
 	// StatusCodes is a histogram of the responses' status codes.
@@ -88,11 +90,15 @@ func (m *Metrics) Add(r *Result) {
 func (m *Metrics) Close() {
 	m.init()
 	m.Rate = float64(m.Requests)
+	m.Throughput = float64(m.success)
 	m.Duration = m.Latest.Sub(m.Earliest)
+	m.Wait = m.End.Sub(m.Latest)
 	if secs := m.Duration.Seconds(); secs > 0 {
 		m.Rate /= secs
+		// No need to check for zero because we know m.Duration > 0
+		m.Throughput /= (m.Duration + m.Wait).Seconds()
 	}
-	m.Wait = m.End.Sub(m.Latest)
+
 	m.BytesIn.Mean = float64(m.BytesIn.Total) / float64(m.Requests)
 	m.BytesOut.Mean = float64(m.BytesOut.Total) / float64(m.Requests)
 	m.Success = float64(m.success) / float64(m.Requests)

lib/metrics_test.go

@@ -57,6 +57,7 @@ func TestMetrics_Add(t *testing.T) {
 		Wait:        duration("10ms"),
 		Requests:    10000,
 		Rate:        1.000100010001,
+		Throughput:  0.6667660098349737,
 		Success:     0.6667,
 		StatusCodes: map[string]int{"500": 3333, "200": 3334, "302": 3333},
 		Errors:      []string{"Internal server error"},

lib/reporters.go

@@ -55,7 +55,7 @@ func NewHistogramReporter(h *Histogram) Reporter {
 // NewTextReporter returns a Reporter that writes out Metrics as aligned,
 // formatted text.
 func NewTextReporter(m *Metrics) Reporter {
-	const fmtstr = "Requests\t[total, rate]\t%d, %.2f\n" +
+	const fmtstr = "Requests\t[total, rate, throughput]\t%d, %.2f, %.2f\n" +
 		"Duration\t[total, attack, wait]\t%s, %s, %s\n" +
 		"Latencies\t[mean, 50, 95, 99, max]\t%s, %s, %s, %s, %s\n" +
 		"Bytes In\t[total, mean]\t%d, %.2f\n" +
@@ -66,7 +66,7 @@ func NewTextReporter(m *Metrics) Reporter {
 	return func(w io.Writer) (err error) {
 		tw := tabwriter.NewWriter(w, 0, 8, 2, ' ', tabwriter.StripEscape)
 		if _, err = fmt.Fprintf(tw, fmtstr,
-			m.Requests, m.Rate,
+			m.Requests, m.Rate, m.Throughput,
 			m.Duration+m.Wait, m.Duration, m.Wait,
 			m.Latencies.Mean, m.Latencies.P50, m.Latencies.P95, m.Latencies.P99, m.Latencies.Max,
 			m.BytesIn.Total, m.BytesIn.Mean,