runtime/pprof: use new profile format for block/mutex profiles

Unlike the legacy text format that outputs the count and the number of
cycles, the pprof tool expects contention profiles to include the count
and the delay time measured in nanoseconds. printCountCycleProfile
performs the conversion from cycles to nanoseconds.
(See parseContention function in
 cmd/vendor/github.com/google/pprof/profile/legacy_profile.go)

Fixes #21474

Change-Id: I8e8fb6ea803822d7eaaf9ecf1df3e236ad225a7b
Reviewed-on: https://go-review.googlesource.com/64410
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 47 insertions, 12 deletions

diff --git a/src/runtime/pprof/pprof.go b/src/runtime/pprof/pprof.go
index 7b875fc488..81681be721 100644
--- a/src/runtime/pprof/pprof.go
+++ b/src/runtime/pprof/pprof.go
@@ -346,6 +346,41 @@ type countProfile interface {
 	Stack(i int) []uintptr
 }
 
+// printCountCycleProfile outputs block profile records (for block or mutex profiles)
+// as the pprof-proto format output. Translations from cycle count to time duration
+// are done because The proto expects count and time (nanoseconds) instead of count
+// and the number of cycles for block, contention profiles.
+func printCountCycleProfile(w io.Writer, countName, cycleName string, records []runtime.BlockProfileRecord) error {
+	// Output profile in protobuf form.
+	b := newProfileBuilder(w)
+	b.pbValueType(tagProfile_PeriodType, countName, "count")
+	b.pb.int64Opt(tagProfile_Period, 1)
+	b.pbValueType(tagProfile_SampleType, countName, "count")
+	b.pbValueType(tagProfile_SampleType, cycleName, "nanoseconds")
+
+	cpuGHz := float64(runtime_cyclesPerSecond()) / 1e9
+
+	values := []int64{0, 0}
+	var locs []uint64
+	for _, r := range records {
+		values[0] = int64(r.Count)
+		values[1] = int64(float64(r.Cycles) / cpuGHz) // to nanoseconds
+		locs = locs[:0]
+		for _, addr := range r.Stack() {
+			// For count profiles, all stack addresses are
+			// return PCs, which is what locForPC expects.
+			l := b.locForPC(addr)
+			if l == 0 { // runtime.goexit
+				continue
+			}
+			locs = append(locs, l)
+		}
+		b.pbSample(values, locs, nil)
+	}
+	b.build()
+	return nil
+}
+
 // printCountProfile prints a countProfile at the specified debug level.
 // The profile will be in compressed proto format unless debug is nonzero.
 func printCountProfile(w io.Writer, debug int, name string, p countProfile) error {
@@ -763,14 +798,14 @@ func writeBlock(w io.Writer, debug int) error {
 
 	sort.Slice(p, func(i, j int) bool { return p[i].Cycles > p[j].Cycles })
 
-	b := bufio.NewWriter(w)
-	var tw *tabwriter.Writer
-	w = b
-	if debug > 0 {
-		tw = tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
-		w = tw
+	if debug <= 0 {
+		return printCountCycleProfile(w, "contentions", "delay", p)
 	}
 
+	b := bufio.NewWriter(w)
+	tw := tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
+	w = tw
+
 	fmt.Fprintf(w, "--- contention:\n")
 	fmt.Fprintf(w, "cycles/second=%v\n", runtime_cyclesPerSecond())
 	for i := range p {
@@ -807,14 +842,14 @@ func writeMutex(w io.Writer, debug int) error {
 
 	sort.Slice(p, func(i, j int) bool { return p[i].Cycles > p[j].Cycles })
 
-	b := bufio.NewWriter(w)
-	var tw *tabwriter.Writer
-	w = b
-	if debug > 0 {
-		tw = tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
-		w = tw
+	if debug <= 0 {
+		return printCountCycleProfile(w, "contentions", "delay", p)
 	}
 
+	b := bufio.NewWriter(w)
+	tw := tabwriter.NewWriter(w, 1, 8, 1, '\t', 0)
+	w = tw
+
 	fmt.Fprintf(w, "--- mutex:\n")
 	fmt.Fprintf(w, "cycles/second=%v\n", runtime_cyclesPerSecond())
 	fmt.Fprintf(w, "sampling period=%d\n", runtime.SetMutexProfileFraction(-1))