Adding upstream version 1.20.14.upstream/1.20.14upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1268 insertions, 0 deletions

diff --git a/src/internal/profile/legacy_profile.go b/src/internal/profile/legacy_profile.go
new file mode 100644
index 0000000..b102c95
--- /dev/null
+++ b/src/internal/profile/legacy_profile.go
@@ -0,0 +1,1268 @@
+// 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.
+
+// This file implements parsers to convert legacy profiles into the
+// profile.proto format.
+
+package profile
+
+import (
+	"bufio"
+	"bytes"
+	"fmt"
+	"io"
+	"math"
+	"regexp"
+	"strconv"
+	"strings"
+)
+
+var (
+	countStartRE = regexp.MustCompile(`\A(\w+) profile: total \d+\n\z`)
+	countRE      = regexp.MustCompile(`\A(\d+) @(( 0x[0-9a-f]+)+)\n\z`)
+
+	heapHeaderRE = regexp.MustCompile(`heap profile: *(\d+): *(\d+) *\[ *(\d+): *(\d+) *\] *@ *(heap[_a-z0-9]*)/?(\d*)`)
+	heapSampleRE = regexp.MustCompile(`(-?\d+): *(-?\d+) *\[ *(\d+): *(\d+) *] @([ x0-9a-f]*)`)
+
+	contentionSampleRE = regexp.MustCompile(`(\d+) *(\d+) @([ x0-9a-f]*)`)
+
+	hexNumberRE = regexp.MustCompile(`0x[0-9a-f]+`)
+
+	growthHeaderRE = regexp.MustCompile(`heap profile: *(\d+): *(\d+) *\[ *(\d+): *(\d+) *\] @ growthz`)
+
+	fragmentationHeaderRE = regexp.MustCompile(`heap profile: *(\d+): *(\d+) *\[ *(\d+): *(\d+) *\] @ fragmentationz`)
+
+	threadzStartRE = regexp.MustCompile(`--- threadz \d+ ---`)
+	threadStartRE  = regexp.MustCompile(`--- Thread ([[:xdigit:]]+) \(name: (.*)/(\d+)\) stack: ---`)
+
+	procMapsRE = regexp.MustCompile(`([[:xdigit:]]+)-([[:xdigit:]]+)\s+([-rwxp]+)\s+([[:xdigit:]]+)\s+([[:xdigit:]]+):([[:xdigit:]]+)\s+([[:digit:]]+)\s*(\S+)?`)
+
+	briefMapsRE = regexp.MustCompile(`\s*([[:xdigit:]]+)-([[:xdigit:]]+):\s*(\S+)(\s.*@)?([[:xdigit:]]+)?`)
+
+	// LegacyHeapAllocated instructs the heapz parsers to use the
+	// allocated memory stats instead of the default in-use memory. Note
+	// that tcmalloc doesn't provide all allocated memory, only in-use
+	// stats.
+	LegacyHeapAllocated bool
+)
+
+func isSpaceOrComment(line string) bool {
+	trimmed := strings.TrimSpace(line)
+	return len(trimmed) == 0 || trimmed[0] == '#'
+}
+
+// parseGoCount parses a Go count profile (e.g., threadcreate or
+// goroutine) and returns a new Profile.
+func parseGoCount(b []byte) (*Profile, error) {
+	r := bytes.NewBuffer(b)
+
+	var line string
+	var err error
+	for {
+		// Skip past comments and empty lines seeking a real header.
+		line, err = r.ReadString('\n')
+		if err != nil {
+			return nil, err
+		}
+		if !isSpaceOrComment(line) {
+			break
+		}
+	}
+
+	m := countStartRE.FindStringSubmatch(line)
+	if m == nil {
+		return nil, errUnrecognized
+	}
+	profileType := m[1]
+	p := &Profile{
+		PeriodType: &ValueType{Type: profileType, Unit: "count"},
+		Period:     1,
+		SampleType: []*ValueType{{Type: profileType, Unit: "count"}},
+	}
+	locations := make(map[uint64]*Location)
+	for {
+		line, err = r.ReadString('\n')
+		if err != nil {
+			if err == io.EOF {
+				break
+			}
+			return nil, err
+		}
+		if isSpaceOrComment(line) {
+			continue
+		}
+		if strings.HasPrefix(line, "---") {
+			break
+		}
+		m := countRE.FindStringSubmatch(line)
+		if m == nil {
+			return nil, errMalformed
+		}
+		n, err := strconv.ParseInt(m[1], 0, 64)
+		if err != nil {
+			return nil, errMalformed
+		}
+		fields := strings.Fields(m[2])
+		locs := make([]*Location, 0, len(fields))
+		for _, stk := range fields {
+			addr, err := strconv.ParseUint(stk, 0, 64)
+			if err != nil {
+				return nil, errMalformed
+			}
+			// Adjust all frames by -1 to land on the call instruction.
+			addr--
+			loc := locations[addr]
+			if loc == nil {
+				loc = &Location{
+					Address: addr,
+				}
+				locations[addr] = loc
+				p.Location = append(p.Location, loc)
+			}
+			locs = append(locs, loc)
+		}
+		p.Sample = append(p.Sample, &Sample{
+			Location: locs,
+			Value:    []int64{n},
+		})
+	}
+
+	if err = parseAdditionalSections(strings.TrimSpace(line), r, p); err != nil {
+		return nil, err
+	}
+	return p, nil
+}
+
+// remapLocationIDs ensures there is a location for each address
+// referenced by a sample, and remaps the samples to point to the new
+// location ids.
+func (p *Profile) remapLocationIDs() {
+	seen := make(map[*Location]bool, len(p.Location))
+	var locs []*Location
+
+	for _, s := range p.Sample {
+		for _, l := range s.Location {
+			if seen[l] {
+				continue
+			}
+			l.ID = uint64(len(locs) + 1)
+			locs = append(locs, l)
+			seen[l] = true
+		}
+	}
+	p.Location = locs
+}
+
+func (p *Profile) remapFunctionIDs() {
+	seen := make(map[*Function]bool, len(p.Function))
+	var fns []*Function
+
+	for _, l := range p.Location {
+		for _, ln := range l.Line {
+			fn := ln.Function
+			if fn == nil || seen[fn] {
+				continue
+			}
+			fn.ID = uint64(len(fns) + 1)
+			fns = append(fns, fn)
+			seen[fn] = true
+		}
+	}
+	p.Function = fns
+}
+
+// remapMappingIDs matches location addresses with existing mappings
+// and updates them appropriately. This is O(N*M), if this ever shows
+// up as a bottleneck, evaluate sorting the mappings and doing a
+// binary search, which would make it O(N*log(M)).
+func (p *Profile) remapMappingIDs() {
+	if len(p.Mapping) == 0 {
+		return
+	}
+
+	// Some profile handlers will incorrectly set regions for the main
+	// executable if its section is remapped. Fix them through heuristics.
+
+	// Remove the initial mapping if named '/anon_hugepage' and has a
+	// consecutive adjacent mapping.
+	if m := p.Mapping[0]; strings.HasPrefix(m.File, "/anon_hugepage") {
+		if len(p.Mapping) > 1 && m.Limit == p.Mapping[1].Start {
+			p.Mapping = p.Mapping[1:]
+		}
+	}
+
+	for _, l := range p.Location {
+		if a := l.Address; a != 0 {
+			for _, m := range p.Mapping {
+				if m.Start <= a && a < m.Limit {
+					l.Mapping = m
+					break
+				}
+			}
+		}
+	}
+
+	// Reset all mapping IDs.
+	for i, m := range p.Mapping {
+		m.ID = uint64(i + 1)
+	}
+}
+
+var cpuInts = []func([]byte) (uint64, []byte){
+	get32l,
+	get32b,
+	get64l,
+	get64b,
+}
+
+func get32l(b []byte) (uint64, []byte) {
+	if len(b) < 4 {
+		return 0, nil
+	}
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24, b[4:]
+}
+
+func get32b(b []byte) (uint64, []byte) {
+	if len(b) < 4 {
+		return 0, nil
+	}
+	return uint64(b[3]) | uint64(b[2])<<8 | uint64(b[1])<<16 | uint64(b[0])<<24, b[4:]
+}
+
+func get64l(b []byte) (uint64, []byte) {
+	if len(b) < 8 {
+		return 0, nil
+	}
+	return uint64(b[0]) | uint64(b[1])<<8 | uint64(b[2])<<16 | uint64(b[3])<<24 | uint64(b[4])<<32 | uint64(b[5])<<40 | uint64(b[6])<<48 | uint64(b[7])<<56, b[8:]
+}
+
+func get64b(b []byte) (uint64, []byte) {
+	if len(b) < 8 {
+		return 0, nil
+	}
+	return uint64(b[7]) | uint64(b[6])<<8 | uint64(b[5])<<16 | uint64(b[4])<<24 | uint64(b[3])<<32 | uint64(b[2])<<40 | uint64(b[1])<<48 | uint64(b[0])<<56, b[8:]
+}
+
+// ParseTracebacks parses a set of tracebacks and returns a newly
+// populated profile. It will accept any text file and generate a
+// Profile out of it with any hex addresses it can identify, including
+// a process map if it can recognize one. Each sample will include a
+// tag "source" with the addresses recognized in string format.
+func ParseTracebacks(b []byte) (*Profile, error) {
+	r := bytes.NewBuffer(b)
+
+	p := &Profile{
+		PeriodType: &ValueType{Type: "trace", Unit: "count"},
+		Period:     1,
+		SampleType: []*ValueType{
+			{Type: "trace", Unit: "count"},
+		},
+	}
+
+	var sources []string
+	var sloc []*Location
+
+	locs := make(map[uint64]*Location)
+	for {
+		l, err := r.ReadString('\n')
+		if err != nil {
+			if err != io.EOF {
+				return nil, err
+			}
+			if l == "" {
+				break
+			}
+		}
+		if sectionTrigger(l) == memoryMapSection {
+			break
+		}
+		if s, addrs := extractHexAddresses(l); len(s) > 0 {
+			for _, addr := range addrs {
+				// Addresses from stack traces point to the next instruction after
+				// each call. Adjust by -1 to land somewhere on the actual call.
+				addr--
+				loc := locs[addr]
+				if locs[addr] == nil {
+					loc = &Location{
+						Address: addr,
+					}
+					p.Location = append(p.Location, loc)
+					locs[addr] = loc
+				}
+				sloc = append(sloc, loc)
+			}
+
+			sources = append(sources, s...)
+		} else {
+			if len(sources) > 0 || len(sloc) > 0 {
+				addTracebackSample(sloc, sources, p)
+				sloc, sources = nil, nil
+			}
+		}
+	}
+
+	// Add final sample to save any leftover data.
+	if len(sources) > 0 || len(sloc) > 0 {
+		addTracebackSample(sloc, sources, p)
+	}
+
+	if err := p.ParseMemoryMap(r); err != nil {
+		return nil, err
+	}
+	return p, nil
+}
+
+func addTracebackSample(l []*Location, s []string, p *Profile) {
+	p.Sample = append(p.Sample,
+		&Sample{
+			Value:    []int64{1},
+			Location: l,
+			Label:    map[string][]string{"source": s},
+		})
+}
+
+// parseCPU parses a profilez legacy profile and returns a newly
+// populated Profile.
+//
+// The general format for profilez samples is a sequence of words in
+// binary format. The first words are a header with the following data:
+//
+//	1st word -- 0
+//	2nd word -- 3
+//	3rd word -- 0 if a c++ application, 1 if a java application.
+//	4th word -- Sampling period (in microseconds).
+//	5th word -- Padding.
+func parseCPU(b []byte) (*Profile, error) {
+	var parse func([]byte) (uint64, []byte)
+	var n1, n2, n3, n4, n5 uint64
+	for _, parse = range cpuInts {
+		var tmp []byte
+		n1, tmp = parse(b)
+		n2, tmp = parse(tmp)
+		n3, tmp = parse(tmp)
+		n4, tmp = parse(tmp)
+		n5, tmp = parse(tmp)
+
+		if tmp != nil && n1 == 0 && n2 == 3 && n3 == 0 && n4 > 0 && n5 == 0 {
+			b = tmp
+			return cpuProfile(b, int64(n4), parse)
+		}
+	}
+	return nil, errUnrecognized
+}
+
+// cpuProfile returns a new Profile from C++ profilez data.
+// b is the profile bytes after the header, period is the profiling
+// period, and parse is a function to parse 8-byte chunks from the
+// profile in its native endianness.
+func cpuProfile(b []byte, period int64, parse func(b []byte) (uint64, []byte)) (*Profile, error) {
+	p := &Profile{
+		Period:     period * 1000,
+		PeriodType: &ValueType{Type: "cpu", Unit: "nanoseconds"},
+		SampleType: []*ValueType{
+			{Type: "samples", Unit: "count"},
+			{Type: "cpu", Unit: "nanoseconds"},
+		},
+	}
+	var err error
+	if b, _, err = parseCPUSamples(b, parse, true, p); err != nil {
+		return nil, err
+	}
+
+	// If all samples have the same second-to-the-bottom frame, it
+	// strongly suggests that it is an uninteresting artifact of
+	// measurement -- a stack frame pushed by the signal handler. The
+	// bottom frame is always correct as it is picked up from the signal
+	// structure, not the stack. Check if this is the case and if so,
+	// remove.
+	if len(p.Sample) > 1 && len(p.Sample[0].Location) > 1 {
+		allSame := true
+		id1 := p.Sample[0].Location[1].Address
+		for _, s := range p.Sample {
+			if len(s.Location) < 2 || id1 != s.Location[1].Address {
+				allSame = false
+				break
+			}
+		}
+		if allSame {
+			for _, s := range p.Sample {
+				s.Location = append(s.Location[:1], s.Location[2:]...)
+			}
+		}
+	}
+
+	if err := p.ParseMemoryMap(bytes.NewBuffer(b)); err != nil {
+		return nil, err
+	}
+	return p, nil
+}
+
+// parseCPUSamples parses a collection of profilez samples from a
+// profile.
+//
+// profilez samples are a repeated sequence of stack frames of the
+// form:
+//
+//	1st word -- The number of times this stack was encountered.
+//	2nd word -- The size of the stack (StackSize).
+//	3rd word -- The first address on the stack.
+//	...
+//	StackSize + 2 -- The last address on the stack
+//
+// The last stack trace is of the form:
+//
+//	1st word -- 0
+//	2nd word -- 1
+//	3rd word -- 0
+//
+// Addresses from stack traces may point to the next instruction after
+// each call. Optionally adjust by -1 to land somewhere on the actual
+// call (except for the leaf, which is not a call).
+func parseCPUSamples(b []byte, parse func(b []byte) (uint64, []byte), adjust bool, p *Profile) ([]byte, map[uint64]*Location, error) {
+	locs := make(map[uint64]*Location)
+	for len(b) > 0 {
+		var count, nstk uint64
+		count, b = parse(b)
+		nstk, b = parse(b)
+		if b == nil || nstk > uint64(len(b)/4) {
+			return nil, nil, errUnrecognized
+		}
+		var sloc []*Location
+		addrs := make([]uint64, nstk)
+		for i := 0; i < int(nstk); i++ {
+			addrs[i], b = parse(b)
+		}
+
+		if count == 0 && nstk == 1 && addrs[0] == 0 {
+			// End of data marker
+			break
+		}
+		for i, addr := range addrs {
+			if adjust && i > 0 {
+				addr--
+			}
+			loc := locs[addr]
+			if loc == nil {
+				loc = &Location{
+					Address: addr,
+				}
+				locs[addr] = loc
+				p.Location = append(p.Location, loc)
+			}
+			sloc = append(sloc, loc)
+		}
+		p.Sample = append(p.Sample,
+			&Sample{
+				Value:    []int64{int64(count), int64(count) * p.Period},
+				Location: sloc,
+			})
+	}
+	// Reached the end without finding the EOD marker.
+	return b, locs, nil
+}
+
+// parseHeap parses a heapz legacy or a growthz profile and
+// returns a newly populated Profile.
+func parseHeap(b []byte) (p *Profile, err error) {
+	r := bytes.NewBuffer(b)
+	l, err := r.ReadString('\n')
+	if err != nil {
+		return nil, errUnrecognized
+	}
+
+	sampling := ""
+
+	if header := heapHeaderRE.FindStringSubmatch(l); header != nil {
+		p = &Profile{
+			SampleType: []*ValueType{
+				{Type: "objects", Unit: "count"},
+				{Type: "space", Unit: "bytes"},
+			},
+			PeriodType: &ValueType{Type: "objects", Unit: "bytes"},
+		}
+
+		var period int64
+		if len(header[6]) > 0 {
+			if period, err = strconv.ParseInt(header[6], 10, 64); err != nil {
+				return nil, errUnrecognized
+			}
+		}
+
+		switch header[5] {
+		case "heapz_v2", "heap_v2":
+			sampling, p.Period = "v2", period
+		case "heapprofile":
+			sampling, p.Period = "", 1
+		case "heap":
+			sampling, p.Period = "v2", period/2
+		default:
+			return nil, errUnrecognized
+		}
+	} else if header = growthHeaderRE.FindStringSubmatch(l); header != nil {
+		p = &Profile{
+			SampleType: []*ValueType{
+				{Type: "objects", Unit: "count"},
+				{Type: "space", Unit: "bytes"},
+			},
+			PeriodType: &ValueType{Type: "heapgrowth", Unit: "count"},
+			Period:     1,
+		}
+	} else if header = fragmentationHeaderRE.FindStringSubmatch(l); header != nil {
+		p = &Profile{
+			SampleType: []*ValueType{
+				{Type: "objects", Unit: "count"},
+				{Type: "space", Unit: "bytes"},
+			},
+			PeriodType: &ValueType{Type: "allocations", Unit: "count"},
+			Period:     1,
+		}
+	} else {
+		return nil, errUnrecognized
+	}
+
+	if LegacyHeapAllocated {
+		for _, st := range p.SampleType {
+			st.Type = "alloc_" + st.Type
+		}
+	} else {
+		for _, st := range p.SampleType {
+			st.Type = "inuse_" + st.Type
+		}
+	}
+
+	locs := make(map[uint64]*Location)
+	for {
+		l, err = r.ReadString('\n')
+		if err != nil {
+			if err != io.EOF {
+				return nil, err
+			}
+
+			if l == "" {
+				break
+			}
+		}
+
+		if isSpaceOrComment(l) {
+			continue
+		}
+		l = strings.TrimSpace(l)
+
+		if sectionTrigger(l) != unrecognizedSection {
+			break
+		}
+
+		value, blocksize, addrs, err := parseHeapSample(l, p.Period, sampling)
+		if err != nil {
+			return nil, err
+		}
+		var sloc []*Location
+		for _, addr := range addrs {
+			// Addresses from stack traces point to the next instruction after
+			// each call. Adjust by -1 to land somewhere on the actual call.
+			addr--
+			loc := locs[addr]
+			if locs[addr] == nil {
+				loc = &Location{
+					Address: addr,
+				}
+				p.Location = append(p.Location, loc)
+				locs[addr] = loc
+			}
+			sloc = append(sloc, loc)
+		}
+
+		p.Sample = append(p.Sample, &Sample{
+			Value:    value,
+			Location: sloc,
+			NumLabel: map[string][]int64{"bytes": {blocksize}},
+		})
+	}
+
+	if err = parseAdditionalSections(l, r, p); err != nil {
+		return nil, err
+	}
+	return p, nil
+}
+
+// parseHeapSample parses a single row from a heap profile into a new Sample.
+func parseHeapSample(line string, rate int64, sampling string) (value []int64, blocksize int64, addrs []uint64, err error) {
+	sampleData := heapSampleRE.FindStringSubmatch(line)
+	if len(sampleData) != 6 {
+		return value, blocksize, addrs, fmt.Errorf("unexpected number of sample values: got %d, want 6", len(sampleData))
+	}
+
+	// Use first two values by default; tcmalloc sampling generates the
+	// same value for both, only the older heap-profile collect separate
+	// stats for in-use and allocated objects.
+	valueIndex := 1
+	if LegacyHeapAllocated {
+		valueIndex = 3
+	}
+
+	var v1, v2 int64
+	if v1, err = strconv.ParseInt(sampleData[valueIndex], 10, 64); err != nil {
+		return value, blocksize, addrs, fmt.Errorf("malformed sample: %s: %v", line, err)
+	}
+	if v2, err = strconv.ParseInt(sampleData[valueIndex+1], 10, 64); err != nil {
+		return value, blocksize, addrs, fmt.Errorf("malformed sample: %s: %v", line, err)
+	}
+
+	if v1 == 0 {
+		if v2 != 0 {
+			return value, blocksize, addrs, fmt.Errorf("allocation count was 0 but allocation bytes was %d", v2)
+		}
+	} else {
+		blocksize = v2 / v1
+		if sampling == "v2" {
+			v1, v2 = scaleHeapSample(v1, v2, rate)
+		}
+	}
+
+	value = []int64{v1, v2}
+	addrs = parseHexAddresses(sampleData[5])
+
+	return value, blocksize, addrs, nil
+}
+
+// extractHexAddresses extracts hex numbers from a string and returns
+// them, together with their numeric value, in a slice.
+func extractHexAddresses(s string) ([]string, []uint64) {
+	hexStrings := hexNumberRE.FindAllString(s, -1)
+	var ids []uint64
+	for _, s := range hexStrings {
+		if id, err := strconv.ParseUint(s, 0, 64); err == nil {
+			ids = append(ids, id)
+		} else {
+			// Do not expect any parsing failures due to the regexp matching.
+			panic("failed to parse hex value:" + s)
+		}
+	}
+	return hexStrings, ids
+}
+
+// parseHexAddresses parses hex numbers from a string and returns them
+// in a slice.
+func parseHexAddresses(s string) []uint64 {
+	_, ids := extractHexAddresses(s)
+	return ids
+}
+
+// scaleHeapSample adjusts the data from a heapz Sample to
+// account for its probability of appearing in the collected
+// data. heapz profiles are a sampling of the memory allocations
+// requests in a program. We estimate the unsampled value by dividing
+// each collected sample by its probability of appearing in the
+// profile. heapz v2 profiles rely on a poisson process to determine
+// which samples to collect, based on the desired average collection
+// rate R. The probability of a sample of size S to appear in that
+// profile is 1-exp(-S/R).
+func scaleHeapSample(count, size, rate int64) (int64, int64) {
+	if count == 0 || size == 0 {
+		return 0, 0
+	}
+
+	if rate <= 1 {
+		// if rate==1 all samples were collected so no adjustment is needed.
+		// if rate<1 treat as unknown and skip scaling.
+		return count, size
+	}
+
+	avgSize := float64(size) / float64(count)
+	scale := 1 / (1 - math.Exp(-avgSize/float64(rate)))
+
+	return int64(float64(count) * scale), int64(float64(size) * scale)
+}
+
+// parseContention parses a mutex or contention profile. There are 2 cases:
+// "--- contentionz " for legacy C++ profiles (and backwards compatibility)
+// "--- mutex:" or "--- contention:" for profiles generated by the Go runtime.
+// This code converts the text output from runtime into a *Profile. (In the future
+// the runtime might write a serialized Profile directly making this unnecessary.)
+func parseContention(b []byte) (*Profile, error) {
+	r := bytes.NewBuffer(b)
+	var l string
+	var err error
+	for {
+		// Skip past comments and empty lines seeking a real header.
+		l, err = r.ReadString('\n')
+		if err != nil {
+			return nil, err
+		}
+		if !isSpaceOrComment(l) {
+			break
+		}
+	}
+
+	if strings.HasPrefix(l, "--- contentionz ") {
+		return parseCppContention(r)
+	} else if strings.HasPrefix(l, "--- mutex:") {
+		return parseCppContention(r)
+	} else if strings.HasPrefix(l, "--- contention:") {
+		return parseCppContention(r)
+	}
+	return nil, errUnrecognized
+}
+
+// parseCppContention parses the output from synchronization_profiling.cc
+// for backward compatibility, and the compatible (non-debug) block profile
+// output from the Go runtime.
+func parseCppContention(r *bytes.Buffer) (*Profile, error) {
+	p := &Profile{
+		PeriodType: &ValueType{Type: "contentions", Unit: "count"},
+		Period:     1,
+		SampleType: []*ValueType{
+			{Type: "contentions", Unit: "count"},
+			{Type: "delay", Unit: "nanoseconds"},
+		},
+	}
+
+	var cpuHz int64
+	var l string
+	var err error
+	// Parse text of the form "attribute = value" before the samples.
+	const delimiter = '='
+	for {
+		l, err = r.ReadString('\n')
+		if err != nil {
+			if err != io.EOF {
+				return nil, err
+			}
+
+			if l == "" {
+				break
+			}
+		}
+		if isSpaceOrComment(l) {
+			continue
+		}
+
+		if l = strings.TrimSpace(l); l == "" {
+			continue
+		}
+
+		if strings.HasPrefix(l, "---") {
+			break
+		}
+
+		index := strings.IndexByte(l, delimiter)
+		if index < 0 {
+			break
+		}
+		key := l[:index]
+		val := l[index+1:]
+
+		key, val = strings.TrimSpace(key), strings.TrimSpace(val)
+		var err error
+		switch key {
+		case "cycles/second":
+			if cpuHz, err = strconv.ParseInt(val, 0, 64); err != nil {
+				return nil, errUnrecognized
+			}
+		case "sampling period":
+			if p.Period, err = strconv.ParseInt(val, 0, 64); err != nil {
+				return nil, errUnrecognized
+			}
+		case "ms since reset":
+			ms, err := strconv.ParseInt(val, 0, 64)
+			if err != nil {
+				return nil, errUnrecognized
+			}
+			p.DurationNanos = ms * 1000 * 1000
+		case "format":
+			// CPP contentionz profiles don't have format.
+			return nil, errUnrecognized
+		case "resolution":
+			// CPP contentionz profiles don't have resolution.
+			return nil, errUnrecognized
+		case "discarded samples":
+		default:
+			return nil, errUnrecognized
+		}
+	}
+
+	locs := make(map[uint64]*Location)
+	for {
+		if !isSpaceOrComment(l) {
+			if l = strings.TrimSpace(l); strings.HasPrefix(l, "---") {
+				break
+			}
+			value, addrs, err := parseContentionSample(l, p.Period, cpuHz)
+			if err != nil {
+				return nil, err
+			}
+			var sloc []*Location
+			for _, addr := range addrs {
+				// Addresses from stack traces point to the next instruction after
+				// each call. Adjust by -1 to land somewhere on the actual call.
+				addr--
+				loc := locs[addr]
+				if locs[addr] == nil {
+					loc = &Location{
+						Address: addr,
+					}
+					p.Location = append(p.Location, loc)
+					locs[addr] = loc
+				}
+				sloc = append(sloc, loc)
+			}
+			p.Sample = append(p.Sample, &Sample{
+				Value:    value,
+				Location: sloc,
+			})
+		}
+
+		if l, err = r.ReadString('\n'); err != nil {
+			if err != io.EOF {
+				return nil, err
+			}
+			if l == "" {
+				break
+			}
+		}
+	}
+
+	if err = parseAdditionalSections(l, r, p); err != nil {
+		return nil, err
+	}
+
+	return p, nil
+}
+
+// parseContentionSample parses a single row from a contention profile
+// into a new Sample.
+func parseContentionSample(line string, period, cpuHz int64) (value []int64, addrs []uint64, err error) {
+	sampleData := contentionSampleRE.FindStringSubmatch(line)
+	if sampleData == nil {
+		return value, addrs, errUnrecognized
+	}
+
+	v1, err := strconv.ParseInt(sampleData[1], 10, 64)
+	if err != nil {
+		return value, addrs, fmt.Errorf("malformed sample: %s: %v", line, err)
+	}
+	v2, err := strconv.ParseInt(sampleData[2], 10, 64)
+	if err != nil {
+		return value, addrs, fmt.Errorf("malformed sample: %s: %v", line, err)
+	}
+
+	// Unsample values if period and cpuHz are available.
+	// - Delays are scaled to cycles and then to nanoseconds.
+	// - Contentions are scaled to cycles.
+	if period > 0 {
+		if cpuHz > 0 {
+			cpuGHz := float64(cpuHz) / 1e9
+			v1 = int64(float64(v1) * float64(period) / cpuGHz)
+		}
+		v2 = v2 * period
+	}
+
+	value = []int64{v2, v1}
+	addrs = parseHexAddresses(sampleData[3])
+
+	return value, addrs, nil
+}
+
+// parseThread parses a Threadz profile and returns a new Profile.
+func parseThread(b []byte) (*Profile, error) {
+	r := bytes.NewBuffer(b)
+
+	var line string
+	var err error
+	for {
+		// Skip past comments and empty lines seeking a real header.
+		line, err = r.ReadString('\n')
+		if err != nil {
+			return nil, err
+		}
+		if !isSpaceOrComment(line) {
+			break
+		}
+	}
+
+	if m := threadzStartRE.FindStringSubmatch(line); m != nil {
+		// Advance over initial comments until first stack trace.
+		for {
+			line, err = r.ReadString('\n')
+			if err != nil {
+				if err != io.EOF {
+					return nil, err
+				}
+
+				if line == "" {
+					break
+				}
+			}
+			if sectionTrigger(line) != unrecognizedSection || line[0] == '-' {
+				break
+			}
+		}
+	} else if t := threadStartRE.FindStringSubmatch(line); len(t) != 4 {
+		return nil, errUnrecognized
+	}
+
+	p := &Profile{
+		SampleType: []*ValueType{{Type: "thread", Unit: "count"}},
+		PeriodType: &ValueType{Type: "thread", Unit: "count"},
+		Period:     1,
+	}
+
+	locs := make(map[uint64]*Location)
+	// Recognize each thread and populate profile samples.
+	for sectionTrigger(line) == unrecognizedSection {
+		if strings.HasPrefix(line, "---- no stack trace for") {
+			line = ""
+			break
+		}
+		if t := threadStartRE.FindStringSubmatch(line); len(t) != 4 {
+			return nil, errUnrecognized
+		}
+
+		var addrs []uint64
+		line, addrs, err = parseThreadSample(r)
+		if err != nil {
+			return nil, errUnrecognized
+		}
+		if len(addrs) == 0 {
+			// We got a --same as previous threads--. Bump counters.
+			if len(p.Sample) > 0 {
+				s := p.Sample[len(p.Sample)-1]
+				s.Value[0]++
+			}
+			continue
+		}
+
+		var sloc []*Location
+		for _, addr := range addrs {
+			// Addresses from stack traces point to the next instruction after
+			// each call. Adjust by -1 to land somewhere on the actual call.
+			addr--
+			loc := locs[addr]
+			if locs[addr] == nil {
+				loc = &Location{
+					Address: addr,
+				}
+				p.Location = append(p.Location, loc)
+				locs[addr] = loc
+			}
+			sloc = append(sloc, loc)
+		}
+
+		p.Sample = append(p.Sample, &Sample{
+			Value:    []int64{1},
+			Location: sloc,
+		})
+	}
+
+	if err = parseAdditionalSections(line, r, p); err != nil {
+		return nil, err
+	}
+
+	return p, nil
+}
+
+// parseThreadSample parses a symbolized or unsymbolized stack trace.
+// Returns the first line after the traceback, the sample (or nil if
+// it hits a 'same-as-previous' marker) and an error.
+func parseThreadSample(b *bytes.Buffer) (nextl string, addrs []uint64, err error) {
+	var l string
+	sameAsPrevious := false
+	for {
+		if l, err = b.ReadString('\n'); err != nil {
+			if err != io.EOF {
+				return "", nil, err
+			}
+			if l == "" {
+				break
+			}
+		}
+		if l = strings.TrimSpace(l); l == "" {
+			continue
+		}
+
+		if strings.HasPrefix(l, "---") {
+			break
+		}
+		if strings.Contains(l, "same as previous thread") {
+			sameAsPrevious = true
+			continue
+		}
+
+		addrs = append(addrs, parseHexAddresses(l)...)
+	}
+
+	if sameAsPrevious {
+		return l, nil, nil
+	}
+	return l, addrs, nil
+}
+
+// parseAdditionalSections parses any additional sections in the
+// profile, ignoring any unrecognized sections.
+func parseAdditionalSections(l string, b *bytes.Buffer, p *Profile) (err error) {
+	for {
+		if sectionTrigger(l) == memoryMapSection {
+			break
+		}
+		// Ignore any unrecognized sections.
+		if l, err := b.ReadString('\n'); err != nil {
+			if err != io.EOF {
+				return err
+			}
+			if l == "" {
+				break
+			}
+		}
+	}
+	return p.ParseMemoryMap(b)
+}
+
+// ParseMemoryMap parses a memory map in the format of
+// /proc/self/maps, and overrides the mappings in the current profile.
+// It renumbers the samples and locations in the profile correspondingly.
+func (p *Profile) ParseMemoryMap(rd io.Reader) error {
+	b := bufio.NewReader(rd)
+
+	var attrs []string
+	var r *strings.Replacer
+	const delimiter = '='
+	for {
+		l, err := b.ReadString('\n')
+		if err != nil {
+			if err != io.EOF {
+				return err
+			}
+			if l == "" {
+				break
+			}
+		}
+		if l = strings.TrimSpace(l); l == "" {
+			continue
+		}
+
+		if r != nil {
+			l = r.Replace(l)
+		}
+		m, err := parseMappingEntry(l)
+		if err != nil {
+			if err == errUnrecognized {
+				// Recognize assignments of the form: attr=value, and replace
+				// $attr with value on subsequent mappings.
+				idx := strings.IndexByte(l, delimiter)
+				if idx >= 0 {
+					attr := l[:idx]
+					value := l[idx+1:]
+					attrs = append(attrs, "$"+strings.TrimSpace(attr), strings.TrimSpace(value))
+					r = strings.NewReplacer(attrs...)
+				}
+				// Ignore any unrecognized entries
+				continue
+			}
+			return err
+		}
+		if m == nil || (m.File == "" && len(p.Mapping) != 0) {
+			// In some cases the first entry may include the address range
+			// but not the name of the file. It should be followed by
+			// another entry with the name.
+			continue
+		}
+		if len(p.Mapping) == 1 && p.Mapping[0].File == "" {
+			// Update the name if this is the entry following that empty one.
+			p.Mapping[0].File = m.File
+			continue
+		}
+		p.Mapping = append(p.Mapping, m)
+	}
+	p.remapLocationIDs()
+	p.remapFunctionIDs()
+	p.remapMappingIDs()
+	return nil
+}
+
+func parseMappingEntry(l string) (*Mapping, error) {
+	mapping := &Mapping{}
+	var err error
+	if me := procMapsRE.FindStringSubmatch(l); len(me) == 9 {
+		if !strings.Contains(me[3], "x") {
+			// Skip non-executable entries.
+			return nil, nil
+		}
+		if mapping.Start, err = strconv.ParseUint(me[1], 16, 64); err != nil {
+			return nil, errUnrecognized
+		}
+		if mapping.Limit, err = strconv.ParseUint(me[2], 16, 64); err != nil {
+			return nil, errUnrecognized
+		}
+		if me[4] != "" {
+			if mapping.Offset, err = strconv.ParseUint(me[4], 16, 64); err != nil {
+				return nil, errUnrecognized
+			}
+		}
+		mapping.File = me[8]
+		return mapping, nil
+	}
+
+	if me := briefMapsRE.FindStringSubmatch(l); len(me) == 6 {
+		if mapping.Start, err = strconv.ParseUint(me[1], 16, 64); err != nil {
+			return nil, errUnrecognized
+		}
+		if mapping.Limit, err = strconv.ParseUint(me[2], 16, 64); err != nil {
+			return nil, errUnrecognized
+		}
+		mapping.File = me[3]
+		if me[5] != "" {
+			if mapping.Offset, err = strconv.ParseUint(me[5], 16, 64); err != nil {
+				return nil, errUnrecognized
+			}
+		}
+		return mapping, nil
+	}
+
+	return nil, errUnrecognized
+}
+
+type sectionType int
+
+const (
+	unrecognizedSection sectionType = iota
+	memoryMapSection
+)
+
+var memoryMapTriggers = []string{
+	"--- Memory map: ---",
+	"MAPPED_LIBRARIES:",
+}
+
+func sectionTrigger(line string) sectionType {
+	for _, trigger := range memoryMapTriggers {
+		if strings.Contains(line, trigger) {
+			return memoryMapSection
+		}
+	}
+	return unrecognizedSection
+}
+
+func (p *Profile) addLegacyFrameInfo() {
+	switch {
+	case isProfileType(p, heapzSampleTypes) ||
+		isProfileType(p, heapzInUseSampleTypes) ||
+		isProfileType(p, heapzAllocSampleTypes):
+		p.DropFrames, p.KeepFrames = allocRxStr, allocSkipRxStr
+	case isProfileType(p, contentionzSampleTypes):
+		p.DropFrames, p.KeepFrames = lockRxStr, ""
+	default:
+		p.DropFrames, p.KeepFrames = cpuProfilerRxStr, ""
+	}
+}
+
+var heapzSampleTypes = []string{"allocations", "size"} // early Go pprof profiles
+var heapzInUseSampleTypes = []string{"inuse_objects", "inuse_space"}
+var heapzAllocSampleTypes = []string{"alloc_objects", "alloc_space"}
+var contentionzSampleTypes = []string{"contentions", "delay"}
+
+func isProfileType(p *Profile, t []string) bool {
+	st := p.SampleType
+	if len(st) != len(t) {
+		return false
+	}
+
+	for i := range st {
+		if st[i].Type != t[i] {
+			return false
+		}
+	}
+	return true
+}
+
+var allocRxStr = strings.Join([]string{
+	// POSIX entry points.
+	`calloc`,
+	`cfree`,
+	`malloc`,
+	`free`,
+	`memalign`,
+	`do_memalign`,
+	`(__)?posix_memalign`,
+	`pvalloc`,
+	`valloc`,
+	`realloc`,
+
+	// TC malloc.
+	`tcmalloc::.*`,
+	`tc_calloc`,
+	`tc_cfree`,
+	`tc_malloc`,
+	`tc_free`,
+	`tc_memalign`,
+	`tc_posix_memalign`,
+	`tc_pvalloc`,
+	`tc_valloc`,
+	`tc_realloc`,
+	`tc_new`,
+	`tc_delete`,
+	`tc_newarray`,
+	`tc_deletearray`,
+	`tc_new_nothrow`,
+	`tc_newarray_nothrow`,
+
+	// Memory-allocation routines on OS X.
+	`malloc_zone_malloc`,
+	`malloc_zone_calloc`,
+	`malloc_zone_valloc`,
+	`malloc_zone_realloc`,
+	`malloc_zone_memalign`,
+	`malloc_zone_free`,
+
+	// Go runtime
+	`runtime\..*`,
+
+	// Other misc. memory allocation routines
+	`BaseArena::.*`,
+	`(::)?do_malloc_no_errno`,
+	`(::)?do_malloc_pages`,
+	`(::)?do_malloc`,
+	`DoSampledAllocation`,
+	`MallocedMemBlock::MallocedMemBlock`,
+	`_M_allocate`,
+	`__builtin_(vec_)?delete`,
+	`__builtin_(vec_)?new`,
+	`__gnu_cxx::new_allocator::allocate`,
+	`__libc_malloc`,
+	`__malloc_alloc_template::allocate`,
+	`allocate`,
+	`cpp_alloc`,
+	`operator new(\[\])?`,
+	`simple_alloc::allocate`,
+}, `|`)
+
+var allocSkipRxStr = strings.Join([]string{
+	// Preserve Go runtime frames that appear in the middle/bottom of
+	// the stack.
+	`runtime\.panic`,
+	`runtime\.reflectcall`,
+	`runtime\.call[0-9]*`,
+}, `|`)
+
+var cpuProfilerRxStr = strings.Join([]string{
+	`ProfileData::Add`,
+	`ProfileData::prof_handler`,
+	`CpuProfiler::prof_handler`,
+	`__pthread_sighandler`,
+	`__restore`,
+}, `|`)
+
+var lockRxStr = strings.Join([]string{
+	`RecordLockProfileData`,
+	`(base::)?RecordLockProfileData.*`,
+	`(base::)?SubmitMutexProfileData.*`,
+	`(base::)?SubmitSpinLockProfileData.*`,
+	`(Mutex::)?AwaitCommon.*`,
+	`(Mutex::)?Unlock.*`,
+	`(Mutex::)?UnlockSlow.*`,
+	`(Mutex::)?ReaderUnlock.*`,
+	`(MutexLock::)?~MutexLock.*`,
+	`(SpinLock::)?Unlock.*`,
+	`(SpinLock::)?SlowUnlock.*`,
+	`(SpinLockHolder::)?~SpinLockHolder.*`,
+}, `|`)