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cmd/trace/v2,internal/trace: use correct frame for identifying gorout…
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…ines

To determine the identity of a goroutine for displaying in the trace UI,
we should use the root frame from a call stack. This will be the
starting function for the goroutine and is the same for each call stack
from a given goroutine. The new tracer no longer includes starting PCs
for goroutines which existed at the start of tracing, so we can't use a
PC for grouping together goroutines any more. Instead, we just use the
name of the entry function for grouping.

Fixes golang#65574

Change-Id: I5324653316f1acf0ab90c30680f181060ea45dd7
Reviewed-on: https://go-review.googlesource.com/c/go/+/562455
Reviewed-by: Michael Knyszek <mknyszek@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
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@nsrip-dd @mknyszek
nsrip-dd authored and mknyszek committed Feb 9, 2024
1 parent 2057ad0 commit a517131
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Showing 4 changed files with 44 additions and 50 deletions.
43 changes: 14 additions & 29 deletions src/cmd/trace/v2/goroutines.go
View file
Expand Up @@ -17,39 +17,30 @@ import (
"net/http"
"slices"
"sort"
"strconv"
"strings"
"time"
)

// GoroutinesHandlerFunc returns a HandlerFunc that serves list of goroutine groups.
func GoroutinesHandlerFunc(summaries map[tracev2.GoID]*trace.GoroutineSummary) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
// goroutineGroup describes a group of goroutines grouped by start PC.
// goroutineGroup describes a group of goroutines grouped by name.
type goroutineGroup struct {
ID uint64 // Unique identifier (PC).
Name string // Start function.
N int // Total number of goroutines in this group.
ExecTime time.Duration // Total execution time of all goroutines in this group.
}
// Accumulate groups by PC.
groupsByPC := make(map[uint64]goroutineGroup)
// Accumulate groups by Name.
groupsByName := make(map[string]goroutineGroup)
for _, summary := range summaries {
group := groupsByPC[summary.PC]
group.ID = summary.PC
group := groupsByName[summary.Name]
group.Name = summary.Name
group.N++
group.ExecTime += summary.ExecTime
groupsByPC[summary.PC] = group
groupsByName[summary.Name] = group
}
var groups []goroutineGroup
for pc, group := range groupsByPC {
group.ID = pc
// If goroutine didn't run during the trace (no sampled PC),
// the v.ID and v.Name will be zero value.
if group.ID == 0 && group.Name == "" {
group.Name = "(Inactive, no stack trace sampled)"
}
for _, group := range groupsByName {
groups = append(groups, group)
}
slices.SortFunc(groups, func(a, b goroutineGroup) int {
Expand Down Expand Up @@ -92,7 +83,7 @@ Click a start location to view more details about that group.<br>
</tr>
{{range $}}
<tr>
<td><code><a href="/goroutine?id={{.ID}}">{{.Name}}</a></code></td>
<td><code><a href="/goroutine?name={{.Name}}">{{or .Name "(Inactive, no stack trace sampled)"}}</a></code></td>
<td>{{.N}}</td>
<td>{{.ExecTime}}</td>
</tr>
Expand All @@ -106,11 +97,7 @@ Click a start location to view more details about that group.<br>
// goroutines in a particular group.
func GoroutineHandler(summaries map[tracev2.GoID]*trace.GoroutineSummary) http.HandlerFunc {
return func(w http.ResponseWriter, r *http.Request) {
pc, err := strconv.ParseUint(r.FormValue("id"), 10, 64)
if err != nil {
http.Error(w, fmt.Sprintf("failed to parse id parameter '%v': %v", r.FormValue("id"), err), http.StatusInternalServerError)
return
}
goroutineName := r.FormValue("name")

type goroutine struct {
*trace.GoroutineSummary
Expand All @@ -130,7 +117,7 @@ func GoroutineHandler(summaries map[tracev2.GoID]*trace.GoroutineSummary) http.H
for _, summary := range summaries {
totalExecTime += summary.ExecTime

if summary.PC != pc {
if summary.Name != goroutineName {
continue
}
nonOverlappingStats := summary.NonOverlappingStats()
Expand Down Expand Up @@ -198,9 +185,8 @@ func GoroutineHandler(summaries map[tracev2.GoID]*trace.GoroutineSummary) http.H
}
sort.Strings(allRangeStats)

err = templGoroutine.Execute(w, struct {
err := templGoroutine.Execute(w, struct {
Name string
PC uint64
N int
ExecTimePercent string
MaxTotal time.Duration
Expand All @@ -209,7 +195,6 @@ func GoroutineHandler(summaries map[tracev2.GoID]*trace.GoroutineSummary) http.H
RangeStats []string
}{
Name: name,
PC: pc,
N: len(goroutines),
ExecTimePercent: execTimePercent,
MaxTotal: maxTotalTime,
Expand Down Expand Up @@ -339,19 +324,19 @@ Table of contents
</tr>
<tr>
<td>Network wait profile:</td>
<td> <a href="/io?id={{.PC}}">graph</a> <a href="/io?id={{.PC}}&raw=1" download="io.profile">(download)</a></td>
<td> <a href="/io?name={{.Name}}">graph</a> <a href="/io?name={{.Name}}&raw=1" download="io.profile">(download)</a></td>
</tr>
<tr>
<td>Sync block profile:</td>
<td> <a href="/block?id={{.PC}}">graph</a> <a href="/block?id={{.PC}}&raw=1" download="block.profile">(download)</a></td>
<td> <a href="/block?name={{.Name}}">graph</a> <a href="/block?name={{.Name}}&raw=1" download="block.profile">(download)</a></td>
</tr>
<tr>
<td>Syscall profile:</td>
<td> <a href="/syscall?id={{.PC}}">graph</a> <a href="/syscall?id={{.PC}}&raw=1" download="syscall.profile">(download)</a></td>
<td> <a href="/syscall?name={{.Name}}">graph</a> <a href="/syscall?name={{.Name}}&raw=1" download="syscall.profile">(download)</a></td>
</tr>
<tr>
<td>Scheduler wait profile:</td>
<td> <a href="/sched?id={{.PC}}">graph</a> <a href="/sched?id={{.PC}}&raw=1" download="sched.profile">(download)</a></td>
<td> <a href="/sched?name={{.Name}}">graph</a> <a href="/sched?name={{.Name}}&raw=1" download="sched.profile">(download)</a></td>
</tr>
</table>
Expand Down
23 changes: 7 additions & 16 deletions src/cmd/trace/v2/pprof.go
View file
Expand Up @@ -14,15 +14,14 @@ import (
tracev2 "internal/trace/v2"
"net/http"
"slices"
"strconv"
"strings"
"time"
)

func pprofByGoroutine(compute computePprofFunc, t *parsedTrace) traceviewer.ProfileFunc {
return func(r *http.Request) ([]traceviewer.ProfileRecord, error) {
id := r.FormValue("id")
gToIntervals, err := pprofMatchingGoroutines(id, t)
name := r.FormValue("name")
gToIntervals, err := pprofMatchingGoroutines(name, t)
if err != nil {
return nil, err
}
Expand All @@ -44,20 +43,12 @@ func pprofByRegion(compute computePprofFunc, t *parsedTrace) traceviewer.Profile
}
}

// pprofMatchingGoroutines parses the goroutine type id string (i.e. pc)
// and returns the ids of goroutines of the matching type and its interval.
// pprofMatchingGoroutines returns the ids of goroutines of the matching name and its interval.
// If the id string is empty, returns nil without an error.
func pprofMatchingGoroutines(id string, t *parsedTrace) (map[tracev2.GoID][]interval, error) {
if id == "" {
return nil, nil
}
pc, err := strconv.ParseUint(id, 10, 64) // id is string
if err != nil {
return nil, fmt.Errorf("invalid goroutine type: %v", id)
}
func pprofMatchingGoroutines(name string, t *parsedTrace) (map[tracev2.GoID][]interval, error) {
res := make(map[tracev2.GoID][]interval)
for _, g := range t.summary.Goroutines {
if g.PC != pc {
if g.Name != name {
continue
}
endTime := g.EndTime
Expand All @@ -66,8 +57,8 @@ func pprofMatchingGoroutines(id string, t *parsedTrace) (map[tracev2.GoID][]inte
}
res[g.ID] = []interval{{start: g.StartTime, end: endTime}}
}
if len(res) == 0 && id != "" {
return nil, fmt.Errorf("failed to find matching goroutines for ID: %s", id)
if len(res) == 0 {
return nil, fmt.Errorf("failed to find matching goroutines for name: %s", name)
}
return res, nil
}
Expand Down
15 changes: 10 additions & 5 deletions src/internal/trace/summary.go
View file
Expand Up @@ -21,7 +21,7 @@ type Summary struct {
type GoroutineSummary struct {
ID tracev2.GoID
Name string // A non-unique human-friendly identifier for the goroutine.
PC uint64 // The start PC of the goroutine.
PC uint64 // The first PC we saw for the entry function of the goroutine
CreationTime tracev2.Time // Timestamp of the first appearance in the trace.
StartTime tracev2.Time // Timestamp of the first time it started running. 0 if the goroutine never ran.
EndTime tracev2.Time // Timestamp of when the goroutine exited. 0 if the goroutine never exited.
Expand Down Expand Up @@ -385,20 +385,25 @@ func (s *Summarizer) Event(ev *tracev2.Event) {
}

// The goroutine hasn't been identified yet. Take the transition stack
// and identify the goroutine by the bottom-most frame of that stack.
// This bottom-most frame will be identical for all transitions on this
// and identify the goroutine by the root frame of that stack.
// This root frame will be identical for all transitions on this
// goroutine, because it represents its immutable start point.
if g.PC == 0 {
if g.Name == "" {
stk := st.Stack
if stk != tracev2.NoStack {
var frame tracev2.StackFrame
var ok bool
stk.Frames(func(f tracev2.StackFrame) bool {
frame = f
ok = true
return false
return true
})
if ok {
// NB: this PC won't actually be consistent for
// goroutines which existed at the start of the
// trace. The UI doesn't use it directly; this
// mainly serves as an indication that we
// actually saw a call stack for the goroutine
g.PC = frame.PC
g.Name = frame.Func
}
Expand Down
13 changes: 13 additions & 0 deletions src/internal/trace/summary_test.go
View file
Expand Up @@ -18,6 +18,10 @@ func TestSummarizeGoroutinesTrace(t *testing.T) {
hasSyncBlockTime bool
hasGCMarkAssistTime bool
)

assertContainsGoroutine(t, summaries, "runtime.gcBgMarkWorker")
assertContainsGoroutine(t, summaries, "main.main.func1")

for _, summary := range summaries {
basicGoroutineSummaryChecks(t, summary)
hasSchedWaitTime = hasSchedWaitTime || summary.SchedWaitTime > 0
Expand Down Expand Up @@ -232,6 +236,15 @@ func TestSummarizeTasksTrace(t *testing.T) {
}
}

func assertContainsGoroutine(t *testing.T, summaries map[tracev2.GoID]*GoroutineSummary, name string) {
for _, summary := range summaries {
if summary.Name == name {
return
}
}
t.Errorf("missing goroutine %s", name)
}

func basicGoroutineSummaryChecks(t *testing.T, summary *GoroutineSummary) {
if summary.ID == tracev2.NoGoroutine {
t.Error("summary found for no goroutine")
Expand Down

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