Merge pull request #3608 from thaJeztah/formatstats_optimize

Small performance optimizations for formatting stats

cli/command/container/formatter_stats.go

@@ -1,7 +1,7 @@
 package container
 
 import (
-	"fmt"
+	"strconv"
 	"sync"
 
 	"github.com/docker/cli/cli/command/formatter"
@@ -43,7 +43,7 @@ type StatsEntry struct {
 
 // Stats represents an entity to store containers statistics synchronously
 type Stats struct {
-	mutex sync.Mutex
+	mutex sync.RWMutex
 	StatsEntry
 	err error
 }
@@ -51,8 +51,8 @@ type Stats struct {
 // GetError returns the container statistics error.
 // This is used to determine whether the statistics are valid or not
 func (cs *Stats) GetError() error {
-	cs.mutex.Lock()
+	cs.mutex.RLock()
-	defer cs.mutex.Unlock()
+	defer cs.mutex.RUnlock()
 	return cs.err
 }
 
@@ -94,8 +94,8 @@ func (cs *Stats) SetStatistics(s StatsEntry) {
 
 // GetStatistics returns container statistics with other meta data such as the container name
 func (cs *Stats) GetStatistics() StatsEntry {
-	cs.mutex.Lock()
+	cs.mutex.RLock()
-	defer cs.mutex.Unlock()
+	defer cs.mutex.RUnlock()
 	return cs.StatsEntry
 }
 
@@ -183,7 +183,7 @@ func (c *statsContext) CPUPerc() string {
 	if c.s.IsInvalid {
 		return "--"
 	}
-	return fmt.Sprintf("%.2f%%", c.s.CPUPercentage)
+	return formatPercentage(c.s.CPUPercentage)
 }
 
 func (c *statsContext) MemUsage() string {
@@ -193,33 +193,37 @@ func (c *statsContext) MemUsage() string {
 	if c.os == winOSType {
 		return units.BytesSize(c.s.Memory)
 	}
-	return fmt.Sprintf("%s / %s", units.BytesSize(c.s.Memory), units.BytesSize(c.s.MemoryLimit))
+	return units.BytesSize(c.s.Memory) + " / " + units.BytesSize(c.s.MemoryLimit)
 }
 
 func (c *statsContext) MemPerc() string {
 	if c.s.IsInvalid || c.os == winOSType {
 		return "--"
 	}
-	return fmt.Sprintf("%.2f%%", c.s.MemoryPercentage)
+	return formatPercentage(c.s.MemoryPercentage)
 }
 
 func (c *statsContext) NetIO() string {
 	if c.s.IsInvalid {
 		return "--"
 	}
-	return fmt.Sprintf("%s / %s", units.HumanSizeWithPrecision(c.s.NetworkRx, 3), units.HumanSizeWithPrecision(c.s.NetworkTx, 3))
+	return units.HumanSizeWithPrecision(c.s.NetworkRx, 3) + " / " + units.HumanSizeWithPrecision(c.s.NetworkTx, 3)
 }
 
 func (c *statsContext) BlockIO() string {
 	if c.s.IsInvalid {
 		return "--"
 	}
-	return fmt.Sprintf("%s / %s", units.HumanSizeWithPrecision(c.s.BlockRead, 3), units.HumanSizeWithPrecision(c.s.BlockWrite, 3))
+	return units.HumanSizeWithPrecision(c.s.BlockRead, 3) + " / " + units.HumanSizeWithPrecision(c.s.BlockWrite, 3)
 }
 
 func (c *statsContext) PIDs() string {
 	if c.s.IsInvalid || c.os == winOSType {
 		return "--"
 	}
-	return fmt.Sprintf("%d", c.s.PidsCurrent)
+	return strconv.FormatUint(c.s.PidsCurrent, 10)
+}
+
+func formatPercentage(val float64) string {
+	return strconv.FormatFloat(val, 'f', 2, 64) + "%"
 }

cli/command/container/formatter_stats_test.go

@@ -308,3 +308,38 @@ func TestContainerStatsContextWriteTrunc(t *testing.T) {
 		out.Reset()
 	}
 }
+
+func BenchmarkStatsFormat(b *testing.B) {
+	b.ReportAllocs()
+	stats := genStats()
+
+	for i := 0; i < b.N; i++ {
+		for _, s := range stats {
+			_ = s.CPUPerc()
+			_ = s.MemUsage()
+			_ = s.MemPerc()
+			_ = s.NetIO()
+			_ = s.BlockIO()
+			_ = s.PIDs()
+		}
+	}
+}
+
+func genStats() []statsContext {
+	entry := statsContext{s: StatsEntry{
+		CPUPercentage:    12.3456789,
+		Memory:           123.456789,
+		MemoryLimit:      987.654321,
+		MemoryPercentage: 12.3456789,
+		BlockRead:        123.456789,
+		BlockWrite:       987.654321,
+		NetworkRx:        123.456789,
+		NetworkTx:        987.654321,
+		PidsCurrent:      123456789,
+	}}
+	stats := make([]statsContext, 100)
+	for i := 0; i < 100; i++ {
+		stats = append(stats, entry)
+	}
+	return stats
+}

cli/command/container/stats.go

@@ -184,13 +184,13 @@ func runStats(dockerCli command.Cli, opts *statsOptions) error {
 		waitFirst.Wait()
 
 		var errs []string
-		cStats.mu.Lock()
+		cStats.mu.RLock()
 		for _, c := range cStats.cs {
 			if err := c.GetError(); err != nil {
 				errs = append(errs, err.Error())
 			}
 		}
-		cStats.mu.Unlock()
+		cStats.mu.RUnlock()
 		if len(errs) > 0 {
 			return errors.New(strings.Join(errs, "\n"))
 		}
@@ -221,11 +221,11 @@ func runStats(dockerCli command.Cli, opts *statsOptions) error {
 	for range ticker.C {
 		cleanScreen()
 		ccstats := []StatsEntry{}
-		cStats.mu.Lock()
+		cStats.mu.RLock()
 		for _, c := range cStats.cs {
 			ccstats = append(ccstats, c.GetStatistics())
 		}
-		cStats.mu.Unlock()
+		cStats.mu.RUnlock()
 		if err = statsFormatWrite(statsCtx, ccstats, daemonOSType, !opts.noTrunc); err != nil {
 			break
 		}

cli/command/container/stats_helpers.go

@@ -14,7 +14,7 @@ import (
 )
 
 type stats struct {
-	mu sync.Mutex
+	mu sync.RWMutex
 	cs []*Stats
 }