dynamically generate CPU counts for metrics

CHANGELOG-developer.next.asciidoc

@@ -52,6 +52,7 @@ The list below covers the major changes between 7.0.0-rc2 and master only.
 - Replace `ACKCount`, `ACKEvents`, and `ACKLastEvent` callbacks with `ACKHandler` and interface in `beat.ClientConfig`. {pull}19632[19632]
 - Remove global ACK handler support via `SetACKHandler` from publisher pipeline. {pull}19632[19632]
 - Make implementing `Close` required for `reader.Reader` interfaces. {pull}20455[20455]
+- Remove `NumCPU` as clients should update the CPU count on the fly in case of config changes in a VM. {pull}23154[23154]
 
 ==== Bugfixes
 

libbeat/cmd/instance/metrics/metrics.go

@@ -264,7 +264,7 @@ func reportSystemCPUUsage(_ monitoring.Mode, V monitoring.Visitor) {
 	V.OnRegistryStart()
 	defer V.OnRegistryFinished()
 
-	monitoring.ReportInt(V, "cores", int64(process.NumCPU))
+	monitoring.ReportInt(V, "cores", int64(runtime.NumCPU()))
 }
 
 func reportRuntime(_ monitoring.Mode, V monitoring.Visitor) {

libbeat/metric/system/cpu/cpu.go

@@ -26,12 +26,6 @@ import (
 	sigar "github.com/elastic/gosigar"
 )
 
-var (
-	// NumCores is the number of CPU cores in the system. Changes to operating
-	// system CPU allocation after process startup are not reflected.
-	NumCores = runtime.NumCPU()
-)
-
 // CPU Monitor
 
 // Monitor is used to monitor the overall CPU usage of the system.
@@ -83,16 +77,16 @@ type Metrics struct {
 }
 
 // NormalizedPercentages returns CPU percentage usage information that is
-// normalized by the number of CPU cores (NumCores). The values will range from
+// normalized by the number of CPU cores. The values will range from
 // 0 to 100%.
 func (m *Metrics) NormalizedPercentages() Percentages {
 	return cpuPercentages(m.previousSample, m.currentSample, 1)
 }
 
 // Percentages returns CPU percentage usage information. The values range from
-// 0 to 100% * NumCores.
+// 0 to 100% * NumCPU.
 func (m *Metrics) Percentages() Percentages {
-	return cpuPercentages(m.previousSample, m.currentSample, NumCores)
+	return cpuPercentages(m.previousSample, m.currentSample, runtime.NumCPU())
 }
 
 // cpuPercentages calculates the amount of CPU time used between the two given
@@ -215,7 +209,7 @@ type LoadAverages struct {
 }
 
 // Averages return the CPU load averages. These values should range from
-// 0 to NumCores.
+// 0 to NumCPU.
 func (m *LoadMetrics) Averages() LoadAverages {
 	return LoadAverages{
 		OneMinute:     common.Round(m.sample.One, common.DefaultDecimalPlacesCount),
@@ -224,12 +218,13 @@ func (m *LoadMetrics) Averages() LoadAverages {
 	}
 }
 
-// NormalizedAverages return the CPU load averages normalized by the NumCores.
+// NormalizedAverages return the CPU load averages normalized by the NumCPU.
 // These values should range from 0 to 1.
 func (m *LoadMetrics) NormalizedAverages() LoadAverages {
+	cpus := runtime.NumCPU()
 	return LoadAverages{
-		OneMinute:     common.Round(m.sample.One/float64(NumCores), common.DefaultDecimalPlacesCount),
-		FiveMinute:    common.Round(m.sample.Five/float64(NumCores), common.DefaultDecimalPlacesCount),
-		FifteenMinute: common.Round(m.sample.Fifteen/float64(NumCores), common.DefaultDecimalPlacesCount),
+		OneMinute:     common.Round(m.sample.One/float64(cpus), common.DefaultDecimalPlacesCount),
+		FiveMinute:    common.Round(m.sample.Five/float64(cpus), common.DefaultDecimalPlacesCount),
+		FifteenMinute: common.Round(m.sample.Fifteen/float64(cpus), common.DefaultDecimalPlacesCount),
 	}
 }

libbeat/metric/system/cpu/cpu_test.go

@@ -29,6 +29,12 @@ import (
 	"github.com/elastic/gosigar"
 )
 
+var (
+	// numCores is the number of CPU cores in the system. Changes to operating
+	// system CPU allocation after process startup are not reflected.
+	numCores = runtime.NumCPU()
+)
+
 func TestMonitorSample(t *testing.T) {
 	cpu := &Monitor{lastSample: &gosigar.Cpu{}}
 	s, err := cpu.Sample()
@@ -55,7 +61,7 @@ func TestMonitorSample(t *testing.T) {
 }
 
 func TestCoresMonitorSample(t *testing.T) {
-	cores := &CoresMonitor{lastSample: make([]gosigar.Cpu, NumCores)}
+	cores := &CoresMonitor{lastSample: make([]gosigar.Cpu, numCores)}
 	sample, err := cores.Sample()
 	if err != nil {
 		t.Fatal(err)
@@ -102,8 +108,8 @@ func TestMetricsRounding(t *testing.T) {
 // TestMetricsPercentages tests that Metrics returns the correct
 // percentages and normalized percentages.
 func TestMetricsPercentages(t *testing.T) {
-	NumCores = 10
-	defer func() { NumCores = runtime.NumCPU() }()
+	numCores = 10
+	defer func() { numCores = runtime.NumCPU() }()
 
 	// This test simulates 30% user and 70% system (normalized), or 3% and 7%
 	// respectively when there are 10 CPUs.
@@ -132,9 +138,10 @@ func TestMetricsPercentages(t *testing.T) {
 	assert.EqualValues(t, .0, pct.Idle)
 	assert.EqualValues(t, 1., pct.Total)
 
-	pct = sample.Percentages()
-	assert.EqualValues(t, .3*float64(NumCores), pct.User)
-	assert.EqualValues(t, .7*float64(NumCores), pct.System)
-	assert.EqualValues(t, .0*float64(NumCores), pct.Idle)
-	assert.EqualValues(t, 1.*float64(NumCores), pct.Total)
+	//bypass the Metrics API so we can have a constant CPU value
+	pct = cpuPercentages(&s0, &s1, numCores)
+	assert.EqualValues(t, .3*float64(numCores), pct.User)
+	assert.EqualValues(t, .7*float64(numCores), pct.System)
+	assert.EqualValues(t, .0*float64(numCores), pct.Idle)
+	assert.EqualValues(t, 1.*float64(numCores), pct.Total)
 }

libbeat/metric/system/diskio/diskstat_linux.go

@@ -20,10 +20,10 @@
 package diskio
 
 import (
+	"runtime"
+
 	"github.com/pkg/errors"
 	"github.com/shirou/gopsutil/disk"
-
-	"github.com/elastic/beats/v7/libbeat/metric/system/cpu"
 )
 
 // GetCLKTCK emulates the _SC_CLK_TCK syscall
@@ -63,7 +63,7 @@ func (stat *IOStat) CalcIOStatistics(counter disk.IOCountersStat) (IOMetric, err
 	}
 
 	// calculate the delta ms between the CloseSampling and OpenSampling
-	deltams := 1000.0 * float64(stat.curCPU.Total()-stat.lastCPU.Total()) / float64(cpu.NumCores) / float64(GetCLKTCK())
+	deltams := 1000.0 * float64(stat.curCPU.Total()-stat.lastCPU.Total()) / float64(runtime.NumCPU()) / float64(GetCLKTCK())
 	if deltams <= 0 {
 		return IOMetric{}, errors.New("The delta cpu time between close sampling and open sampling is less or equal to 0")
 	}

libbeat/metric/system/process/process.go

@@ -36,9 +36,6 @@ import (
 	sigar "github.com/elastic/gosigar"
 )
 
-// NumCPU is the number of CPUs of the host
-var NumCPU = runtime.NumCPU()
-
 // ProcsMap is a map where the keys are the names of processes and the value is the Process with that name
 type ProcsMap map[int]*Process
 
@@ -365,7 +362,7 @@ func GetProcCPUPercentage(s0, s1 *Process) (normalizedPct, pct, totalPct float64
 		totalCPUDeltaMillis := int64(s1.Cpu.Total - s0.Cpu.Total)
 
 		pct := float64(totalCPUDeltaMillis) / float64(timeDeltaMillis)
-		normalizedPct := pct / float64(NumCPU)
+		normalizedPct := pct / float64(runtime.NumCPU())
 
 		return common.Round(normalizedPct, common.DefaultDecimalPlacesCount),
 			common.Round(pct, common.DefaultDecimalPlacesCount),

libbeat/metric/system/process/process_test.go

@@ -33,6 +33,9 @@ import (
 	"github.com/elastic/gosigar"
 )
 
+// numCPU is the number of CPUs of the host
+var numCPU = runtime.NumCPU()
+
 func TestPids(t *testing.T) {
 	pids, err := Pids()
 
@@ -157,11 +160,14 @@ func TestProcCpuPercentage(t *testing.T) {
 		SampleTime: p1.SampleTime.Add(time.Second),
 	}
 
-	NumCPU = 48
-	defer func() { NumCPU = runtime.NumCPU() }()
-
 	totalPercentNormalized, totalPercent, totalValue := GetProcCPUPercentage(p1, p2)
-	assert.EqualValues(t, 0.0721, totalPercentNormalized)
+	//GetProcCPUPercentage wil return a number that varies based on the host, due to NumCPU()
+	// So "un-normalize" it, then re-normalized with a constant.
+	cpu := float64(runtime.NumCPU())
+	unNormalized := totalPercentNormalized * cpu
+	normalizedTest := common.Round(unNormalized/48, common.DefaultDecimalPlacesCount)
+
+	assert.EqualValues(t, 0.0721, normalizedTest)
 	assert.EqualValues(t, 3.459, totalPercent)
 	assert.EqualValues(t, 14841, totalValue)
 }

metricbeat/module/system/cpu/data.go

@@ -97,7 +97,7 @@ func getPlatformCPUMetrics(sample *cpu.Metrics, selectors []string, event common
 
 // gather CPU metrics
 func collectCPUMetrics(selectors []string, sample *cpu.Metrics) mb.Event {
-	event := common.MapStr{"cores": cpu.NumCores}
+	event := common.MapStr{"cores": runtime.NumCPU()}
 	getPlatformCPUMetrics(sample, selectors, event)
 
 	//generate the host fields here, since we don't want users disabling it.

metricbeat/module/system/load/load.go

@@ -20,6 +20,8 @@
 package load
 
 import (
+	"runtime"
+
 	"github.com/pkg/errors"
 
 	"github.com/elastic/beats/v7/libbeat/common"
@@ -58,7 +60,7 @@ func (m *MetricSet) Fetch(r mb.ReporterV2) error {
 	normAvgs := load.NormalizedAverages()
 
 	event := common.MapStr{
-		"cores": cpu.NumCores,
+		"cores": runtime.NumCPU(),
 		"1":     avgs.OneMinute,
 		"5":     avgs.FiveMinute,
 		"15":    avgs.FifteenMinute,