runtime/pprof: generate heap profiles in compressed proto format

When debug is 0, emit the compressed proto format.
The debug>0 format stays the same.

Updates #16093

Change-Id: I45aa1874a22d34cf44dd4aa78bbff9302381cb34
Reviewed-on: https://go-review.googlesource.com/33422
Run-TryBot: Michael Matloob <matloob@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/runtime/pprof/internal/protopprof/protomemprofile.go

+// Copyright 2016 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.
+
+package protopprof
+
+import (
+	"internal/pprof/profile"
+	"math"
+	"runtime"
+	"time"
+)
+
+// EncodeMemProfile converts MemProfileRecords to a Profile.
+func EncodeMemProfile(mr []runtime.MemProfileRecord, rate int64, t time.Time) *profile.Profile {
+	p := &profile.Profile{
+		Period:     rate,
+		PeriodType: &profile.ValueType{Type: "space", Unit: "bytes"},
+		SampleType: []*profile.ValueType{
+			{Type: "alloc_objects", Unit: "count"},
+			{Type: "alloc_space", Unit: "bytes"},
+			{Type: "inuse_objects", Unit: "count"},
+			{Type: "inuse_space", Unit: "bytes"},
+		},
+		TimeNanos: int64(t.UnixNano()),
+	}
+
+	locs := make(map[uintptr]*profile.Location)
+	for _, r := range mr {
+		stack := r.Stack()
+		sloc := make([]*profile.Location, len(stack))
+		for i, addr := range stack {
+			loc := locs[addr]
+			if loc == nil {
+				loc = &profile.Location{
+					ID:      uint64(len(p.Location) + 1),
+					Address: uint64(addr),
+				}
+				locs[addr] = loc
+				p.Location = append(p.Location, loc)
+			}
+			sloc[i] = loc
+		}
+
+		ao, ab := scaleHeapSample(r.AllocObjects, r.AllocBytes, rate)
+		uo, ub := scaleHeapSample(r.InUseObjects(), r.InUseBytes(), rate)
+
+		p.Sample = append(p.Sample, &profile.Sample{
+			Value:    []int64{ao, ab, uo, ub},
+			Location: sloc,
+		})
+	}
+	if runtime.GOOS == "linux" {
+		addMappings(p)
+	}
+	return p
+}
+
+// scaleHeapSample adjusts the data from a heap Sample to
+// account for its probability of appearing in the collected
+// data. heap 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. heap 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)
+}

src/runtime/pprof/internal/protopprof/protomemprofile_test.go

+// Copyright 2016 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.
+
+package protopprof
+
+import (
+	"bytes"
+	"internal/pprof/profile"
+	"io/ioutil"
+	"reflect"
+	"runtime"
+	"testing"
+	"time"
+)
+
+// TestSampledHeapAllocProfile tests encoding of a memory profile from
+// runtime.MemProfileRecord data.
+func TestSampledHeapAllocProfile(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip("Test requires a system with /proc/self/maps")
+	}
+
+	// Figure out two addresses from /proc/self/maps.
+	mmap, err := ioutil.ReadFile("/proc/self/maps")
+	if err != nil {
+		t.Fatal("Cannot read /proc/self/maps")
+	}
+	rd := bytes.NewReader(mmap)
+	mprof := &profile.Profile{}
+	if err = mprof.ParseMemoryMap(rd); err != nil {
+		t.Fatalf("Cannot parse /proc/self/maps")
+	}
+	if len(mprof.Mapping) < 2 {
+		t.Fatalf("Less than two mappings")
+	}
+	address1 := mprof.Mapping[0].Start
+	address2 := mprof.Mapping[1].Start
+
+	var buf bytes.Buffer
+
+	rec, rate := testMemRecords(address1, address2)
+	p := EncodeMemProfile(rec, rate, time.Now())
+	if err := p.Write(&buf); err != nil {
+		t.Fatalf("Failed to write profile: %v", err)
+	}
+
+	p, err = profile.Parse(&buf)
+	if err != nil {
+		t.Fatalf("Could not parse Profile profile: %v", err)
+	}
+
+	// Expected PeriodType, SampleType and Sample.
+	expectedPeriodType := &profile.ValueType{Type: "space", Unit: "bytes"}
+	expectedSampleType := []*profile.ValueType{
+		{Type: "alloc_objects", Unit: "count"},
+		{Type: "alloc_space", Unit: "bytes"},
+		{Type: "inuse_objects", Unit: "count"},
+		{Type: "inuse_space", Unit: "bytes"},
+	}
+	// Expected samples, with values unsampled according to the profiling rate.
+	expectedSample := []*profile.Sample{
+		{Value: []int64{2050, 2099200, 1537, 1574400}, Location: []*profile.Location{
+			{ID: 1, Mapping: mprof.Mapping[0], Address: address1},
+			{ID: 2, Mapping: mprof.Mapping[1], Address: address2},
+		}},
+		{Value: []int64{1, 829411, 1, 829411}, Location: []*profile.Location{
+			{ID: 3, Mapping: mprof.Mapping[1], Address: address2 + 1},
+			{ID: 4, Mapping: mprof.Mapping[1], Address: address2 + 2},
+		}},
+		{Value: []int64{1, 829411, 0, 0}, Location: []*profile.Location{
+			{ID: 5, Mapping: mprof.Mapping[0], Address: address1 + 1},
+			{ID: 6, Mapping: mprof.Mapping[0], Address: address1 + 2},
+			{ID: 7, Mapping: mprof.Mapping[1], Address: address2 + 3},
+		}},
+	}
+
+	if p.Period != 512*1024 {
+		t.Fatalf("Sampling periods do not match")
+	}
+	if !reflect.DeepEqual(p.PeriodType, expectedPeriodType) {
+		t.Fatalf("Period types do not match")
+	}
+	if !reflect.DeepEqual(p.SampleType, expectedSampleType) {
+		t.Fatalf("Sample types do not match")
+	}
+	if !reflect.DeepEqual(p.Sample, expectedSample) {
+		t.Fatalf("Samples do not match: Expected: %v, Got:%v", getSampleAsString(expectedSample),
+			getSampleAsString(p.Sample))
+	}
+}
+
+func testMemRecords(a1, a2 uint64) ([]runtime.MemProfileRecord, int64) {
+	addr1, addr2 := uintptr(a1), uintptr(a2)
+	rate := int64(512 * 1024)
+	rec := []runtime.MemProfileRecord{
+		{4096, 1024, 4, 1, [32]uintptr{addr1, addr2}},
+		{512 * 1024, 0, 1, 0, [32]uintptr{addr2 + 1, addr2 + 2}},
+		{512 * 1024, 512 * 1024, 1, 1, [32]uintptr{addr1 + 1, addr1 + 2, addr2 + 3}},
+	}
+	return rec, rate
+}

src/runtime/pprof/pprof.go

@@ -485,15 +485,16 @@ func writeHeap(w io.Writer, debug int) error {
 		// Profile grew; try again.
 	}
 
+	if debug == 0 {
+		pp := protopprof.EncodeMemProfile(p, int64(runtime.MemProfileRate), time.Now())
+		return pp.Write(w)
+	}
+
 	sort.Slice(p, func(i, j int) bool { return p[i].InUseBytes() > p[j].InUseBytes() })
 
 	b := bufio.NewWriter(w)
-	var tw *tabwriter.Writer
-	w = b
-	if debug > 0 {
-		tw = tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
-		w = tw
-	}
+	tw := tabwriter.NewWriter(b, 1, 8, 1, '\t', 0)
+	w = tw
 
 	var total runtime.MemProfileRecord
 	for i := range p {
@@ -521,9 +522,7 @@ func writeHeap(w io.Writer, debug int) error {
 			fmt.Fprintf(w, " %#x", pc)
 		}
 		fmt.Fprintf(w, "\n")
-		if debug > 0 {
-			printStackRecord(w, r.Stack(), false)
-		}
+		printStackRecord(w, r.Stack(), false)
 	}
 
 	// Print memstats information too.
@@ -557,9 +556,7 @@ func writeHeap(w io.Writer, debug int) error {
 	fmt.Fprintf(w, "# NumGC = %d\n", s.NumGC)
 	fmt.Fprintf(w, "# DebugGC = %v\n", s.DebugGC)
 
-	if tw != nil {
-		tw.Flush()
-	}
+	tw.Flush()
 	return b.Flush()
 }