runtime/pprof: output CPU profiles in pprof protobuf format

This change buffers the entire profile and converts in one shot
in the profile writer, and could use more memory than necessary
to output protocol buffer formatted profiles. It should be
possible to convert each chunk in a stream (maybe maintaining
some minimal state to output in the end) which could save on
memory usage.

Fixes #16093

Change-Id: I946c6a2b044ae644c72c8bb2d3bd82c415b1a847
Reviewed-on: https://go-review.googlesource.com/33071
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

1 files changed, 30 insertions, 33 deletions

diff --git a/src/runtime/pprof/pprof_test.go b/src/runtime/pprof/pprof_test.go
index a683a03211..c19ea3507d 100644
--- a/src/runtime/pprof/pprof_test.go
+++ b/src/runtime/pprof/pprof_test.go
@@ -9,6 +9,7 @@ package pprof_test
 import (
 	"bytes"
 	"fmt"
+	"internal/pprof/profile"
 	"internal/testenv"
 	"math/big"
 	"os"
@@ -20,7 +21,6 @@ import (
 	"sync"
 	"testing"
 	"time"
-	"unsafe"
 )
 
 func cpuHogger(f func(), dur time.Duration) {
@@ -87,40 +87,17 @@ func TestCPUProfileMultithreaded(t *testing.T) {
 }
 
 func parseProfile(t *testing.T, valBytes []byte, f func(uintptr, []uintptr)) {
-	// Convert []byte to []uintptr.
-	l := len(valBytes)
-	if i := bytes.Index(valBytes, []byte("\nMAPPED_LIBRARIES:\n")); i >= 0 {
-		l = i
+	p, err := profile.Parse(bytes.NewReader(valBytes))
+	if err != nil {
+		t.Fatal(err)
 	}
-	l /= int(unsafe.Sizeof(uintptr(0)))
-	val := *(*[]uintptr)(unsafe.Pointer(&valBytes))
-	val = val[:l]
-
-	// 5 for the header, 3 for the trailer.
-	if l < 5+3 {
-		t.Logf("profile too short: %#x", val)
-		if badOS[runtime.GOOS] {
-			t.Skipf("ignoring failure on %s; see golang.org/issue/13841", runtime.GOOS)
-			return
+	for _, sample := range p.Sample {
+		count := uintptr(sample.Value[0])
+		stk := make([]uintptr, len(sample.Location))
+		for i := range sample.Location {
+			stk[i] = uintptr(sample.Location[i].Address)
 		}
-		t.FailNow()
-	}
-
-	hd, val, tl := val[:5], val[5:l-3], val[l-3:]
-	if hd[0] != 0 || hd[1] != 3 || hd[2] != 0 || hd[3] != 1e6/100 || hd[4] != 0 {
-		t.Fatalf("unexpected header %#x", hd)
-	}
-
-	if tl[0] != 0 || tl[1] != 1 || tl[2] != 0 {
-		t.Fatalf("malformed end-of-data marker %#x", tl)
-	}
-
-	for len(val) > 0 {
-		if len(val) < 2 || val[0] < 1 || val[1] < 1 || uintptr(len(val)) < 2+val[1] {
-			t.Fatalf("malformed profile.  leftover: %#x", val)
-		}
-		f(val[0], val[2:2+val[1]])
-		val = val[2+val[1]:]
+		f(count, stk)
 	}
 }
 
@@ -674,3 +651,23 @@ func containsInOrder(s string, all ...string) bool {
 	}
 	return true
 }
+
+// Tests that the profiler outputs a parsable protobuf Profile profile.
+func TestCPUProfileParse(t *testing.T) {
+
+	var before, after runtime.MemStats
+	runtime.ReadMemStats(&before)
+	var buf bytes.Buffer
+
+	if err := StartCPUProfile(&buf); err != nil {
+		t.Fatalf("Profile failed: Could not enable CPU profiling: %s\n", err)
+	}
+	time.Sleep(5 * time.Second)
+	StopCPUProfile()
+
+	runtime.ReadMemStats(&after)
+	_, err := profile.Parse(&buf)
+	if err != nil {
+		t.Fatalf("Could not parse Profile profile: %v", err)
+	}
+}