src/cmd/trace/pprof.go - go - Git at Google

 // Copyright 2014 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.

 // Serving of pprof-like profiles.

 package main

 import (
 	"cmp"
 	"fmt"
 	"internal/trace"
 	"internal/trace/traceviewer"
 	"net/http"
 	"slices"
 	"strings"
 	"time"
 )

 func pprofByGoroutine(compute computePprofFunc, t *parsedTrace) traceviewer.ProfileFunc {
 	return func(r *http.Request) ([]traceviewer.ProfileRecord, error) {
 		name := r.FormValue("name")
 		gToIntervals, err := pprofMatchingGoroutines(name, t)
 		if err != nil {
 			return nil, err
 		}
 		return compute(gToIntervals, t.events)
 	}
 }

 func pprofByRegion(compute computePprofFunc, t *parsedTrace) traceviewer.ProfileFunc {
 	return func(r *http.Request) ([]traceviewer.ProfileRecord, error) {
 		filter, err := newRegionFilter(r)
 		if err != nil {
 			return nil, err
 		}
 		gToIntervals, err := pprofMatchingRegions(filter, t)
 		if err != nil {
 			return nil, err
 		}
 		return compute(gToIntervals, t.events)
 	}
 }

 // pprofMatchingGoroutines returns the ids of goroutines of the matching name and its interval.
 // If the id string is empty, returns nil without an error.
 func pprofMatchingGoroutines(name string, t *parsedTrace) (map[trace.GoID][]interval, error) {
 	res := make(map[trace.GoID][]interval)
 	for _, g := range t.summary.Goroutines {
 		if name != "" && g.Name != name {
 			continue
 		}
 		endTime := g.EndTime
 		if g.EndTime == 0 {
 			endTime = t.endTime() // Use the trace end time, since the goroutine is still live then.
 		}
 		res[g.ID] = []interval{{start: g.StartTime, end: endTime}}
 	}
 	if len(res) == 0 {
 		return nil, fmt.Errorf("failed to find matching goroutines for name: %s", name)
 	}
 	return res, nil
 }

 // pprofMatchingRegions returns the time intervals of matching regions
 // grouped by the goroutine id. If the filter is nil, returns nil without an error.
 func pprofMatchingRegions(filter *regionFilter, t *parsedTrace) (map[trace.GoID][]interval, error) {
 	if filter == nil {
 		return nil, nil
 	}

 	gToIntervals := make(map[trace.GoID][]interval)
 	for _, g := range t.summary.Goroutines {
 		for _, r := range g.Regions {
 			if !filter.match(t, r) {
 				continue
 			}
 			gToIntervals[g.ID] = append(gToIntervals[g.ID], regionInterval(t, r))
 		}
 	}

 	for g, intervals := range gToIntervals {
 		// In order to remove nested regions and
 		// consider only the outermost regions,
 		// first, we sort based on the start time
 		// and then scan through to select only the outermost regions.
 		slices.SortFunc(intervals, func(a, b interval) int {
 			if c := cmp.Compare(a.start, b.start); c != 0 {
 				return c
 			}
 			return cmp.Compare(a.end, b.end)
 		})
 		var lastTimestamp trace.Time
 		var n int
 		// Select only the outermost regions.
 		for _, i := range intervals {
 			if lastTimestamp <= i.start {
 				intervals[n] = i // new non-overlapping region starts.
 				lastTimestamp = i.end
 				n++
 			}
 			// Otherwise, skip because this region overlaps with a previous region.
 		}
 		gToIntervals[g] = intervals[:n]
 	}
 	return gToIntervals, nil
 }

 type computePprofFunc func(gToIntervals map[trace.GoID][]interval, events []trace.Event) ([]traceviewer.ProfileRecord, error)

 // computePprofIO returns a computePprofFunc that generates IO pprof-like profile (time spent in
 // IO wait, currently only network blocking event).
 func computePprofIO() computePprofFunc {
 	return makeComputePprofFunc(trace.GoWaiting, func(reason string) bool {
 		return reason == "network"
 	})
 }

 // computePprofBlock returns a computePprofFunc that generates blocking pprof-like profile
 // (time spent blocked on synchronization primitives).
 func computePprofBlock() computePprofFunc {
 	return makeComputePprofFunc(trace.GoWaiting, func(reason string) bool {
 		return strings.Contains(reason, "chan") || strings.Contains(reason, "sync") || strings.Contains(reason, "select")
 	})
 }

 // computePprofSyscall returns a computePprofFunc that generates a syscall pprof-like
 // profile (time spent in syscalls).
 func computePprofSyscall() computePprofFunc {
 	return makeComputePprofFunc(trace.GoSyscall, func(_ string) bool {
 		return true
 	})
 }

 // computePprofSched returns a computePprofFunc that generates a scheduler latency pprof-like profile
 // (time between a goroutine become runnable and actually scheduled for execution).
 func computePprofSched() computePprofFunc {
 	return makeComputePprofFunc(trace.GoRunnable, func(_ string) bool {
 		return true
 	})
 }

 // makeComputePprofFunc returns a computePprofFunc that generates a profile of time goroutines spend
 // in a particular state for the specified reasons.
 func makeComputePprofFunc(state trace.GoState, trackReason func(string) bool) computePprofFunc {
 	return func(gToIntervals map[trace.GoID][]interval, events []trace.Event) ([]traceviewer.ProfileRecord, error) {
 		stacks := newStackMap()
 		tracking := make(map[trace.GoID]*trace.Event)
 		for i := range events {
 			ev := &events[i]

 			// Filter out any non-state-transitions and events without stacks.
 			if ev.Kind() != trace.EventStateTransition {
 				continue
 			}
 			stack := ev.Stack()
 			if stack == trace.NoStack {
 				continue
 			}

 			// The state transition has to apply to a goroutine.
 			st := ev.StateTransition()
 			if st.Resource.Kind != trace.ResourceGoroutine {
 				continue
 			}
 			id := st.Resource.Goroutine()
 			_, new := st.Goroutine()

 			// Check if we're tracking this goroutine.
 			startEv := tracking[id]
 			if startEv == nil {
 				// We're not. Start tracking if the new state
 				// matches what we want and the transition is
 				// for one of the reasons we care about.
 				if new == state && trackReason(st.Reason) {
 					tracking[id] = ev
 				}
 				continue
 			}
 			// We're tracking this goroutine.
 			if new == state {
 				// We're tracking this goroutine, but it's just transitioning
 				// to the same state (this is a no-ip
 				continue
 			}
 			// The goroutine has transitioned out of the state we care about,
 			// so remove it from tracking and record the stack.
 			delete(tracking, id)

 			overlapping := pprofOverlappingDuration(gToIntervals, id, interval{startEv.Time(), ev.Time()})
 			if overlapping > 0 {
 				rec := stacks.getOrAdd(startEv.Stack())
 				rec.Count++
 				rec.Time += overlapping
 			}
 		}
 		return stacks.profile(), nil
 	}
 }

 // pprofOverlappingDuration returns the overlapping duration between
 // the time intervals in gToIntervals and the specified event.
 // If gToIntervals is nil, this simply returns the event's duration.
 func pprofOverlappingDuration(gToIntervals map[trace.GoID][]interval, id trace.GoID, sample interval) time.Duration {
 	if gToIntervals == nil { // No filtering.
 		return sample.duration()
 	}
 	intervals := gToIntervals[id]
 	if len(intervals) == 0 {
 		return 0
 	}

 	var overlapping time.Duration
 	for _, i := range intervals {
 		if o := i.overlap(sample); o > 0 {
 			overlapping += o
 		}
 	}
 	return overlapping
 }

 // interval represents a time interval in the trace.
 type interval struct {
 	start, end trace.Time
 }

 func (i interval) duration() time.Duration {
 	return i.end.Sub(i.start)
 }

 func (i1 interval) overlap(i2 interval) time.Duration {
 	// Assume start1 <= end1 and start2 <= end2
 	if i1.end < i2.start || i2.end < i1.start {
 		return 0
 	}
 	if i1.start < i2.start { // choose the later one
 		i1.start = i2.start
 	}
 	if i1.end > i2.end { // choose the earlier one
 		i1.end = i2.end
 	}
 	return i1.duration()
 }

 // pprofMaxStack is the extent of the deduplication we're willing to do.
 //
 // Because slices aren't comparable and we want to leverage maps for deduplication,
 // we have to choose a fixed constant upper bound on the amount of frames we want
 // to support. In practice this is fine because there's a maximum depth to these
 // stacks anyway.
 const pprofMaxStack = 128

 // stackMap is a map of trace.Stack to some value V.
 type stackMap struct {
 	// stacks contains the full list of stacks in the set, however
 	// it is insufficient for deduplication because trace.Stack
 	// equality is only optimistic. If two trace.Stacks are equal,
 	// then they are guaranteed to be equal in content. If they are
 	// not equal, then they might still be equal in content.
 	stacks map[trace.Stack]*traceviewer.ProfileRecord

 	// pcs is the source-of-truth for deduplication. It is a map of
 	// the actual PCs in the stack to a trace.Stack.
 	pcs map[[pprofMaxStack]uint64]trace.Stack
 }

 func newStackMap() *stackMap {
 	return &stackMap{
 		stacks: make(map[trace.Stack]*traceviewer.ProfileRecord),
 		pcs:    make(map[[pprofMaxStack]uint64]trace.Stack),
 	}
 }

 func (m *stackMap) getOrAdd(stack trace.Stack) *traceviewer.ProfileRecord {
 	// Fast path: check to see if this exact stack is already in the map.
 	if rec, ok := m.stacks[stack]; ok {
 		return rec
 	}
 	// Slow path: the stack may still be in the map.

 	// Grab the stack's PCs as the source-of-truth.
 	var pcs [pprofMaxStack]uint64
 	pcsForStack(stack, &pcs)

 	// Check the source-of-truth.
 	var rec *traceviewer.ProfileRecord
 	if existing, ok := m.pcs[pcs]; ok {
 		// In the map.
 		rec = m.stacks[existing]
 		delete(m.stacks, existing)
 	} else {
 		// Not in the map.
 		rec = new(traceviewer.ProfileRecord)
 	}
 	// Insert regardless of whether we have a match in m.pcs.
 	// Even if we have a match, we want to keep the newest version
 	// of that stack, since we're much more likely tos see it again
 	// as we iterate through the trace linearly. Simultaneously, we
 	// are likely to never see the old stack again.
 	m.pcs[pcs] = stack
 	m.stacks[stack] = rec
 	return rec
 }

 func (m *stackMap) profile() []traceviewer.ProfileRecord {
 	prof := make([]traceviewer.ProfileRecord, 0, len(m.stacks))
 	for stack, record := range m.stacks {
 		rec := *record
 		i := 0
 		stack.Frames(func(frame trace.StackFrame) bool {
 			rec.Stack = append(rec.Stack, &trace.Frame{
 				PC:   frame.PC,
 				Fn:   frame.Func,
 				File: frame.File,
 				Line: int(frame.Line),
 			})
 			i++
 			// Cut this off at pprofMaxStack because that's as far
 			// as our deduplication goes.
 			return i < pprofMaxStack
 		})
 		prof = append(prof, rec)
 	}
 	return prof
 }

 // pcsForStack extracts the first pprofMaxStack PCs from stack into pcs.
 func pcsForStack(stack trace.Stack, pcs *[pprofMaxStack]uint64) {
 	i := 0
 	stack.Frames(func(frame trace.StackFrame) bool {
 		pcs[i] = frame.PC
 		i++
 		return i < len(pcs)
 	})
 }
	// Copyright 2014 The Go Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style
	// license that can be found in the LICENSE file.

	// Serving of pprof-like profiles.

	package main

	import (
	"cmp"
	"fmt"
	"internal/trace"
	"internal/trace/traceviewer"
	"net/http"
	"slices"
	"strings"
	"time"
	)

	func pprofByGoroutine(compute computePprofFunc, t *parsedTrace) traceviewer.ProfileFunc {
	return func(r *http.Request) ([]traceviewer.ProfileRecord, error) {
	name := r.FormValue("name")
	gToIntervals, err := pprofMatchingGoroutines(name, t)
	if err != nil {
	return nil, err
	}
	return compute(gToIntervals, t.events)
	}
	}

	func pprofByRegion(compute computePprofFunc, t *parsedTrace) traceviewer.ProfileFunc {
	return func(r *http.Request) ([]traceviewer.ProfileRecord, error) {
	filter, err := newRegionFilter(r)
	if err != nil {
	return nil, err
	}
	gToIntervals, err := pprofMatchingRegions(filter, t)
	if err != nil {
	return nil, err
	}
	return compute(gToIntervals, t.events)
	}
	}

	// pprofMatchingGoroutines returns the ids of goroutines of the matching name and its interval.
	// If the id string is empty, returns nil without an error.
	func pprofMatchingGoroutines(name string, t *parsedTrace) (map[trace.GoID][]interval, error) {
	res := make(map[trace.GoID][]interval)
	for _, g := range t.summary.Goroutines {
	if name != "" && g.Name != name {
	continue
	}
	endTime := g.EndTime
	if g.EndTime == 0 {
	endTime = t.endTime() // Use the trace end time, since the goroutine is still live then.
	}
	res[g.ID] = []interval{{start: g.StartTime, end: endTime}}
	}
	if len(res) == 0 {
	return nil, fmt.Errorf("failed to find matching goroutines for name: %s", name)
	}
	return res, nil
	}

	// pprofMatchingRegions returns the time intervals of matching regions
	// grouped by the goroutine id. If the filter is nil, returns nil without an error.
	func pprofMatchingRegions(filter regionFilter, t parsedTrace) (map[trace.GoID][]interval, error) {
	if filter == nil {
	return nil, nil
	}

	gToIntervals := make(map[trace.GoID][]interval)
	for _, g := range t.summary.Goroutines {
	for _, r := range g.Regions {
	if !filter.match(t, r) {
	continue
	}
	gToIntervals[g.ID] = append(gToIntervals[g.ID], regionInterval(t, r))
	}
	}

	for g, intervals := range gToIntervals {
	// In order to remove nested regions and
	// consider only the outermost regions,
	// first, we sort based on the start time
	// and then scan through to select only the outermost regions.
	slices.SortFunc(intervals, func(a, b interval) int {
	if c := cmp.Compare(a.start, b.start); c != 0 {
	return c
	}
	return cmp.Compare(a.end, b.end)
	})
	var lastTimestamp trace.Time
	var n int
	// Select only the outermost regions.
	for _, i := range intervals {
	if lastTimestamp <= i.start {
	intervals[n] = i // new non-overlapping region starts.
	lastTimestamp = i.end
	n++
	}
	// Otherwise, skip because this region overlaps with a previous region.
	}
	gToIntervals[g] = intervals[:n]
	}
	return gToIntervals, nil
	}

	type computePprofFunc func(gToIntervals map[trace.GoID][]interval, events []trace.Event) ([]traceviewer.ProfileRecord, error)

	// computePprofIO returns a computePprofFunc that generates IO pprof-like profile (time spent in
	// IO wait, currently only network blocking event).
	func computePprofIO() computePprofFunc {
	return makeComputePprofFunc(trace.GoWaiting, func(reason string) bool {
	return reason == "network"
	})
	}

	// computePprofBlock returns a computePprofFunc that generates blocking pprof-like profile
	// (time spent blocked on synchronization primitives).
	func computePprofBlock() computePprofFunc {
	return makeComputePprofFunc(trace.GoWaiting, func(reason string) bool {
	return strings.Contains(reason, "chan") \|\| strings.Contains(reason, "sync") \|\| strings.Contains(reason, "select")
	})
	}

	// computePprofSyscall returns a computePprofFunc that generates a syscall pprof-like
	// profile (time spent in syscalls).
	func computePprofSyscall() computePprofFunc {
	return makeComputePprofFunc(trace.GoSyscall, func(_ string) bool {
	return true
	})
	}

	// computePprofSched returns a computePprofFunc that generates a scheduler latency pprof-like profile
	// (time between a goroutine become runnable and actually scheduled for execution).
	func computePprofSched() computePprofFunc {
	return makeComputePprofFunc(trace.GoRunnable, func(_ string) bool {
	return true
	})
	}

	// makeComputePprofFunc returns a computePprofFunc that generates a profile of time goroutines spend
	// in a particular state for the specified reasons.
	func makeComputePprofFunc(state trace.GoState, trackReason func(string) bool) computePprofFunc {
	return func(gToIntervals map[trace.GoID][]interval, events []trace.Event) ([]traceviewer.ProfileRecord, error) {
	stacks := newStackMap()
	tracking := make(map[trace.GoID]*trace.Event)
	for i := range events {
	ev := &events[i]

	// Filter out any non-state-transitions and events without stacks.
	if ev.Kind() != trace.EventStateTransition {
	continue
	}
	stack := ev.Stack()
	if stack == trace.NoStack {
	continue
	}

	// The state transition has to apply to a goroutine.
	st := ev.StateTransition()
	if st.Resource.Kind != trace.ResourceGoroutine {
	continue
	}
	id := st.Resource.Goroutine()
	_, new := st.Goroutine()

	// Check if we're tracking this goroutine.
	startEv := tracking[id]
	if startEv == nil {
	// We're not. Start tracking if the new state
	// matches what we want and the transition is
	// for one of the reasons we care about.
	if new == state && trackReason(st.Reason) {
	tracking[id] = ev
	}
	continue
	}
	// We're tracking this goroutine.
	if new == state {
	// We're tracking this goroutine, but it's just transitioning
	// to the same state (this is a no-ip
	continue
	}
	// The goroutine has transitioned out of the state we care about,
	// so remove it from tracking and record the stack.
	delete(tracking, id)

	overlapping := pprofOverlappingDuration(gToIntervals, id, interval{startEv.Time(), ev.Time()})
	if overlapping > 0 {
	rec := stacks.getOrAdd(startEv.Stack())
	rec.Count++
	rec.Time += overlapping
	}
	}
	return stacks.profile(), nil
	}
	}

	// pprofOverlappingDuration returns the overlapping duration between
	// the time intervals in gToIntervals and the specified event.
	// If gToIntervals is nil, this simply returns the event's duration.
	func pprofOverlappingDuration(gToIntervals map[trace.GoID][]interval, id trace.GoID, sample interval) time.Duration {
	if gToIntervals == nil { // No filtering.
	return sample.duration()
	}
	intervals := gToIntervals[id]
	if len(intervals) == 0 {
	return 0
	}

	var overlapping time.Duration
	for _, i := range intervals {
	if o := i.overlap(sample); o > 0 {
	overlapping += o
	}
	}
	return overlapping
	}

	// interval represents a time interval in the trace.
	type interval struct {
	start, end trace.Time
	}

	func (i interval) duration() time.Duration {
	return i.end.Sub(i.start)
	}

	func (i1 interval) overlap(i2 interval) time.Duration {
	// Assume start1 <= end1 and start2 <= end2
	if i1.end < i2.start \|\| i2.end < i1.start {
	return 0
	}
	if i1.start < i2.start { // choose the later one
	i1.start = i2.start
	}
	if i1.end > i2.end { // choose the earlier one
	i1.end = i2.end
	}
	return i1.duration()
	}

	// pprofMaxStack is the extent of the deduplication we're willing to do.
	//
	// Because slices aren't comparable and we want to leverage maps for deduplication,
	// we have to choose a fixed constant upper bound on the amount of frames we want
	// to support. In practice this is fine because there's a maximum depth to these
	// stacks anyway.
	const pprofMaxStack = 128

	// stackMap is a map of trace.Stack to some value V.
	type stackMap struct {
	// stacks contains the full list of stacks in the set, however
	// it is insufficient for deduplication because trace.Stack
	// equality is only optimistic. If two trace.Stacks are equal,
	// then they are guaranteed to be equal in content. If they are
	// not equal, then they might still be equal in content.
	stacks map[trace.Stack]*traceviewer.ProfileRecord

	// pcs is the source-of-truth for deduplication. It is a map of
	// the actual PCs in the stack to a trace.Stack.
	pcs map[[pprofMaxStack]uint64]trace.Stack
	}

	func newStackMap() *stackMap {
	return &stackMap{
	stacks: make(map[trace.Stack]*traceviewer.ProfileRecord),
	pcs: make(map[[pprofMaxStack]uint64]trace.Stack),
	}
	}

	func (m stackMap) getOrAdd(stack trace.Stack) traceviewer.ProfileRecord {
	// Fast path: check to see if this exact stack is already in the map.
	if rec, ok := m.stacks[stack]; ok {
	return rec
	}
	// Slow path: the stack may still be in the map.

	// Grab the stack's PCs as the source-of-truth.
	var pcs [pprofMaxStack]uint64
	pcsForStack(stack, &pcs)

	// Check the source-of-truth.
	var rec *traceviewer.ProfileRecord
	if existing, ok := m.pcs[pcs]; ok {
	// In the map.
	rec = m.stacks[existing]
	delete(m.stacks, existing)
	} else {
	// Not in the map.
	rec = new(traceviewer.ProfileRecord)
	}
	// Insert regardless of whether we have a match in m.pcs.
	// Even if we have a match, we want to keep the newest version
	// of that stack, since we're much more likely tos see it again
	// as we iterate through the trace linearly. Simultaneously, we
	// are likely to never see the old stack again.
	m.pcs[pcs] = stack
	m.stacks[stack] = rec
	return rec
	}

	func (m *stackMap) profile() []traceviewer.ProfileRecord {
	prof := make([]traceviewer.ProfileRecord, 0, len(m.stacks))
	for stack, record := range m.stacks {
	rec := *record
	i := 0
	stack.Frames(func(frame trace.StackFrame) bool {
	rec.Stack = append(rec.Stack, &trace.Frame{
	PC: frame.PC,
	Fn: frame.Func,
	File: frame.File,
	Line: int(frame.Line),
	})
	i++
	// Cut this off at pprofMaxStack because that's as far
	// as our deduplication goes.
	return i < pprofMaxStack
	})
	prof = append(prof, rec)
	}
	return prof
	}

	// pcsForStack extracts the first pprofMaxStack PCs from stack into pcs.
	func pcsForStack(stack trace.Stack, pcs *[pprofMaxStack]uint64) {
	i := 0
	stack.Frames(func(frame trace.StackFrame) bool {
	pcs[i] = frame.PC
	i++
	return i < len(pcs)
	})
	}