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Add GCPauses var kind

This commit is contained in:
Ivan Daniluk 2016-11-12 23:59:56 +01:00
parent f96b3c1045
commit a7619df293
3 changed files with 218 additions and 17 deletions
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150
histogram.go Normal file
View File

@ -0,0 +1,150 @@
package main
type Histogram struct {
Bins []Bin
Maxbins int
Total uint64
}
type Bin struct {
Value, Count uint64
}
// NewHistogram returns a new Histogram with a maximum of n bins.
//
// There is no "optimal" bin count, but somewhere between 20 and 80 bins
// should be sufficient.
func NewHistogram(n int) *Histogram {
return &Histogram{
Bins: make([]Bin, 0),
Maxbins: n,
Total: 0,
}
}
func (h *Histogram) Add(n uint64) {
defer h.trim()
h.Total++
for i := range h.Bins {
if h.Bins[i].Value == n {
h.Bins[i].Count++
return
}
if h.Bins[i].Value > n {
newbin := Bin{Value: n, Count: 1}
head := append(make([]Bin, 0), h.Bins[0:i]...)
head = append(head, newbin)
tail := h.Bins[i:]
h.Bins = append(head, tail...)
return
}
}
h.Bins = append(h.Bins, Bin{Count: 1, Value: n})
}
func (h *Histogram) Quantile(q uint64) int64 {
count := q * h.Total
for i := range h.Bins {
count -= h.Bins[i].Count
if count <= 0 {
return int64(h.Bins[i].Value)
}
}
return -1
}
// CDF returns the value of the cumulative distribution function
// at x
func (h *Histogram) CDF(x uint64) uint64 {
var count uint64
for i := range h.Bins {
if h.Bins[i].Value <= x {
count += h.Bins[i].Count
}
}
return count / h.Total
}
// Mean returns the sample mean of the distribution
func (h *Histogram) Mean() float64 {
if h.Total == 0 {
return 0
}
sum := 0.0
for i := range h.Bins {
sum += float64(h.Bins[i].Value * h.Bins[i].Count)
}
return sum / float64(h.Total)
}
// Variance returns the variance of the distribution
func (h *Histogram) Variance() float64 {
if h.Total == 0 {
return 0
}
sum := 0.0
mean := h.Mean()
for i := range h.Bins {
sum += float64(h.Bins[i].Count * (h.Bins[i].Value - uint64(mean)) * (h.Bins[i].Value - uint64(mean)))
}
return sum / float64(h.Total)
}
func (h *Histogram) Count() uint64 {
return h.Total
}
// trim merges adjacent bins to decrease the bin count to the maximum value
func (h *Histogram) trim() {
for len(h.Bins) > h.Maxbins {
// Find closest bins in terms of value
minDelta := uint64(1e10)
minDeltaIndex := 0
for i := range h.Bins {
if i == 0 {
continue
}
if delta := h.Bins[i].Value - h.Bins[i-1].Value; delta < minDelta {
minDelta = delta
minDeltaIndex = i
}
}
// We need to merge bins minDeltaIndex-1 and minDeltaIndex
totalCount := h.Bins[minDeltaIndex-1].Count + h.Bins[minDeltaIndex].Count
mergedbin := Bin{
Value: (h.Bins[minDeltaIndex-1].Value*
h.Bins[minDeltaIndex-1].Count +
h.Bins[minDeltaIndex].Value*
h.Bins[minDeltaIndex].Count) /
totalCount, // weighted average
Count: totalCount, // summed heights
}
head := append(make([]Bin, 0), h.Bins[0:minDeltaIndex-1]...)
tail := append([]Bin{mergedbin}, h.Bins[minDeltaIndex+1:]...)
h.Bins = append(head, tail...)
}
}
func (h *Histogram) BarchartData() ([]uint64, []int) {
values := make([]uint64, len(h.Bins))
counts := make([]int, len(h.Bins))
for i := 0; i < len(h.Bins); i++ {
values[i] = h.Bins[i].Value
counts[i] = int(h.Bins[i].Count)
}
return values, counts
}

70
var.go
View File

@ -25,6 +25,7 @@ const (
KindMemory
KindDuration
KindString
KindGCPauses
)
// Var represents arbitrary value for variable.
@ -41,6 +42,26 @@ type IntVar interface {
Value() int
}
// NewVar inits new Var object with the given name.
func NewVar(name VarName) Var {
kind := name.Kind()
switch kind {
case KindDefault:
return &Number{}
case KindMemory:
return &Memory{}
case KindDuration:
return &Duration{}
case KindString:
return &String{}
case KindGCPauses:
return &GCPauses{}
default:
return &Number{}
}
}
// Number is a type for numeric values, obtained from JSON.
// In JSON it's always float64, so there is no straightforward way
// to separate float from int, so let's keep everything as float.
@ -131,25 +152,35 @@ func (v *String) Set(j *jason.Value) {
}
}
// TODO: add boolean, timestamp, gcpauses, gcendtimes types
// GCPauses represents GC pauses data.
//
// It uses memstat.PauseNS circular buffer, but lacks
// NumGC information, so we don't know what the start
// and the end. It's enough for most stats, though.
type GCPauses struct {
pauses [256]uint64
}
// NewVar inits new Var object with the given name.
func NewVar(name VarName) Var {
kind := name.Kind()
switch kind {
case KindDefault:
return &Number{}
case KindMemory:
return &Memory{}
case KindDuration:
return &Duration{}
case KindString:
return &String{}
default:
return &Number{}
func (v *GCPauses) Kind() VarKind { return KindGCPauses }
func (v *GCPauses) String() string { return "" }
func (v *GCPauses) Set(j *jason.Value) {
v.pauses = [256]uint64{}
if arr, err := j.Array(); err == nil {
for i := 0; i < len(arr); i++ {
p, _ := arr[i].Int64()
v.pauses[i] = uint64(p)
}
}
}
func (v *GCPauses) Histogram(bins int) *Histogram {
hist := NewHistogram(bins)
for i := 0; i < 256; i++ {
hist.Add(v.pauses[i])
}
return hist
}
// TODO: add boolean, timestamp, gcpauses, gcendtimes types
// ToSlice converts "dot-separated" notation into the "slice of strings".
//
@ -184,8 +215,13 @@ func (v VarName) Long() string {
return string(v)[start:]
}
// Kind returns kind of variable, based on it's name modifiers ("mem:")
// Kind returns kind of variable, based on it's name
// modifiers ("mem:") or full names for special cases.
func (v VarName) Kind() VarKind {
if v.Long() == "memstats.PauseNs" {
return KindGCPauses
}
start := strings.IndexRune(string(v), ':')
if start == -1 {
return KindDefault

15
var_test.go
View File

@ -191,3 +191,18 @@ func TestVarString(t *testing.T) {
t.Fatalf("Expect value to be %s, got %s", want, v.String())
}
}
func TestVarGCPauses(t *testing.T) {
v := &GCPauses{}
v.Set(str2val(t, pauseNSTest))
hist := v.Histogram(20)
if values, _ := hist.BarchartData(); len(values) != 20 {
t.Fatalf("Expect len of values to be 20, got %v", len(values))
}
// TODO: check if it's true mean :)
if want, mean := 67383.87109375, hist.Mean(); mean != want {
t.Fatalf("Expect mean to be be %v, got %v", want, mean)
}
}
const pauseNSTest = "[65916, 92412, 67016, 59076, 55161, 53428, 128675, 90476, 78093, 60473, 64353, 58214, 83926, 64390, 103391, 71275, 76651, 56475, 367180, 184505, 307648, 175680, 129120, 102616, 127322, 224862, 83092, 148607, 122833, 139011, 494885, 97452, 95129, 115403, 119657, 122214, 111744, 115824, 95834, 81927, 91120, 131541, 75511, 135424, 125637, 85784, 107094, 101551, 110081, 80628, 123030, 130343, 128940, 114670, 111470, 75146, 101250, 117553, 112062, 106360, 101543, 108607, 245857, 106147, 108091, 84570, 78700, 117863, 74284, 102977, 83952, 108068, 89709, 115250, 108062, 135150, 84460, 389962, 109881, 79255, 88669, 106366, 90551, 115548, 93409, 124459, 93660, 132709, 70662, 119209, 86984, 118776, 114768, 107875, 70117, 95590, 90558, 86439, 85069, 83155, 89212, 115581, 61221, 78387, 67468, 82099, 107160, 83947, 109817, 113753, 121822, 87682, 104144, 88659, 82247, 91591, 138847, 498527, 121882, 114585, 135840, 111263, 101143, 106915, 100841, 110974, 71145, 97220, 118328, 103716, 115043, 74672, 86126, 106929, 115845, 97969, 118960, 103949, 96019, 80543, 106717, 115346, 114901, 88455, 76337, 107155, 141398, 92871, 120444, 90579, 110057, 94518, 115869, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]"