Fix truncated CPU profiles

Author: simonswine

pkg/pprof/fix_go_profile.go

@@ -20,7 +20,7 @@ func FixGoProfile(p *profilev1.Profile) *profilev1.Profile {
 	// truncated stack traces, if any. Note that repaired stacks
 	// are not deduplicated, so the caller need to normalize the
 	if MayHaveGoHeapTruncatedStacktraces(p) {
-		RepairGoHeapTruncatedStacktraces(p)
+		RepairGoTruncatedStacktraces(p)
 	}
 	return p
 }

pkg/pprof/fix_go_profile_test.go

@@ -10,7 +10,7 @@ import (
 )
 
 func Test_FixGoProfile(t *testing.T) {
-	p, err := OpenFile("testdata/goheapfix/heap_go_truncated_4.pb.gz")
+	p, err := OpenFile("testdata/gotruncatefix/heap_go_truncated_4.pb.gz")
 	require.NoError(t, err)
 
 	f := FixGoProfile(p.Profile)

pkg/pprof/fix_go_heap_truncated.go renamed to pkg/pprof/fix_go_truncated.go

@@ -23,11 +23,20 @@ const (
 // MayHaveGoHeapTruncatedStacktraces reports whether there are
 // any chances that the profile may have truncated stack traces.
 func MayHaveGoHeapTruncatedStacktraces(p *profilev1.Profile) bool {
-	if !hasGoHeapSampleTypes(p) {
+	var minDepth = 0
+
+	if hasGoHeapSampleTypes(p) {
+		// TODO: Go heap profiles in Go 1.23 have a depth limit of 128 frames. At some point we can probably increase/remove this
+		minDepth = 32
+	} else if hasGoCPUSampleTypes(p) {
+		minDepth = 64
+	} else {
 		return false
 	}
-	// Some truncated stacks have depth less than the depth limit (32).
-	const minDepth = 28
+
+	// Some truncated stacks have depth less than the depth limit.
+	minDepth -= 3
+
 	for _, s := range p.Sample {
 		if len(s.LocationId) >= minDepth {
 			return true
@@ -50,7 +59,18 @@ func hasGoHeapSampleTypes(p *profilev1.Profile) bool {
 	return false
 }
 
-// RepairGoHeapTruncatedStacktraces repairs truncated stack traces
+func hasGoCPUSampleTypes(p *profilev1.Profile) bool {
+	for _, st := range p.SampleType {
+		switch p.StringTable[st.Type] {
+		case
+			"cpu":
+			return true
+		}
+	}
+	return false
+}
+
+// RepairGoTruncatedStacktraces repairs truncated stack traces
 // in Go heap profiles.
 //
 // Go heap profile has a depth limit of 32 frames, which often
@@ -66,7 +86,7 @@ func hasGoHeapSampleTypes(p *profilev1.Profile) bool {
 // one by at least 16 frames in a row from the top, and has frames
 // above its root, stack S considered truncated, and the missing part
 // is copied from R.
-func RepairGoHeapTruncatedStacktraces(p *profilev1.Profile) {
+func RepairGoTruncatedStacktraces(p *profilev1.Profile) {
 	// Group stack traces by bottom (closest to the root) locations.
 	// Typically, there are very few groups (a hundred or two).
 	samples, groups := split(p)

pkg/pprof/fix_go_heap_truncated_test.go renamed to pkg/pprof/fix_go_truncated_test.go

@@ -8,23 +8,24 @@ import (
 )
 
 func Benchmark_RepairGoTruncatedStacktraces(b *testing.B) {
-	p, err := OpenFile("testdata/goheapfix/heap_go_truncated_3.pb.gz")
+	p, err := OpenFile("testdata/gotruncatefix/heap_go_truncated_3.pb.gz")
 	require.NoError(b, err)
 	b.ResetTimer()
 	b.ReportAllocs()
 	for i := 0; i < b.N; i++ {
-		RepairGoHeapTruncatedStacktraces(FixGoProfile(p.CloneVT()))
+		RepairGoTruncatedStacktraces(FixGoProfile(p.CloneVT()))
 	}
 }
 
 func Test_UpdateFixtures_RepairGoTruncatedStacktraces(t *testing.T) {
 	t.Skip()
 	t.Helper()
 	paths := []string{
-		"testdata/goheapfix/heap_go_truncated_1.pb.gz", // Cortex.
-		"testdata/goheapfix/heap_go_truncated_2.pb.gz", // Cortex.
-		"testdata/goheapfix/heap_go_truncated_3.pb.gz", // Loki. Pathological.
-		"testdata/goheapfix/heap_go_truncated_4.pb.gz", // Pyroscope.
+		"testdata/gotruncatefix/heap_go_truncated_1.pb.gz", // Cortex.
+		"testdata/gotruncatefix/heap_go_truncated_2.pb.gz", // Cortex.
+		"testdata/gotruncatefix/heap_go_truncated_3.pb.gz", // Loki. Pathological.
+		"testdata/gotruncatefix/heap_go_truncated_4.pb.gz", // Pyroscope.
+		"testdata/gotruncatefix/cpu_go_truncated_1.pb.gz",  // Mimir Querier
 	}
 	for _, path := range paths {
 		func() {
@@ -34,7 +35,7 @@ func Test_UpdateFixtures_RepairGoTruncatedStacktraces(t *testing.T) {
 			require.NoError(t, err, path)
 			defer f.Close()
 			p.Profile = FixGoProfile(p.Profile)
-			RepairGoHeapTruncatedStacktraces(p.Profile)
+			RepairGoTruncatedStacktraces(p.Profile)
 			_, err = p.WriteTo(f)
 			require.NoError(t, err, path)
 		}()