blob: f94586abf3da6cdcb40928d2ea09ccfc01fd5cae [file] [log] [blame]
// Copyright 2014 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 main
import (
_ "net/http/pprof" // Required to use pprof
const usageMessage = "" +
`Usage of 'go tool trace':
Given a trace file produced by 'go test':
go test -trace=trace.out pkg
Open a web browser displaying trace:
go tool trace [flags] [pkg.test] trace.out
Generate a pprof-like profile from the trace:
go tool trace -pprof=TYPE [pkg.test] trace.out
[pkg.test] argument is required for traces produced by Go 1.6 and below.
Go 1.7 does not require the binary argument.
Supported profile types are:
- net: network blocking profile
- sync: synchronization blocking profile
- syscall: syscall blocking profile
- sched: scheduler latency profile
-http=addr: HTTP service address (e.g., ':6060')
-pprof=type: print a pprof-like profile instead
-d: print debug info such as parsed events
Note that while the various profiles available when launching
'go tool trace' work on every browser, the trace viewer itself
(the 'view trace' page) comes from the Chrome/Chromium project
and is only actively tested on that browser.
var (
httpFlag = flag.String("http", "localhost:0", "HTTP service address (e.g., ':6060')")
pprofFlag = flag.String("pprof", "", "print a pprof-like profile instead")
debugFlag = flag.Bool("d", false, "print debug information such as parsed events list")
// The binary file name, left here for serveSVGProfile.
programBinary string
traceFile string
func main() {
flag.Usage = func() {
fmt.Fprintln(os.Stderr, usageMessage)
// Go 1.7 traces embed symbol info and does not require the binary.
// But we optionally accept binary as first arg for Go 1.5 traces.
switch flag.NArg() {
case 1:
traceFile = flag.Arg(0)
case 2:
programBinary = flag.Arg(0)
traceFile = flag.Arg(1)
var pprofFunc func(io.Writer, *http.Request) error
switch *pprofFlag {
case "net":
pprofFunc = pprofByGoroutine(computePprofIO)
case "sync":
pprofFunc = pprofByGoroutine(computePprofBlock)
case "syscall":
pprofFunc = pprofByGoroutine(computePprofSyscall)
case "sched":
pprofFunc = pprofByGoroutine(computePprofSched)
if pprofFunc != nil {
if err := pprofFunc(os.Stdout, &http.Request{}); err != nil {
dief("failed to generate pprof: %v\n", err)
if *pprofFlag != "" {
dief("unknown pprof type %s\n", *pprofFlag)
ln, err := net.Listen("tcp", *httpFlag)
if err != nil {
dief("failed to create server socket: %v\n", err)
log.Print("Parsing trace...")
res, err := parseTrace()
if err != nil {
dief("%v\n", err)
if *debugFlag {
reportMemoryUsage("after parsing trace")
log.Print("Splitting trace...")
ranges = splitTrace(res)
reportMemoryUsage("after spliting trace")
addr := "http://" + ln.Addr().String()
log.Printf("Opening browser. Trace viewer is listening on %s", addr)
// Start http server.
http.HandleFunc("/", httpMain)
err = http.Serve(ln, nil)
dief("failed to start http server: %v\n", err)
var ranges []Range
var loader struct {
once sync.Once
res trace.ParseResult
err error
// parseEvents is a compatibility wrapper that returns only
// the Events part of trace.ParseResult returned by parseTrace.
func parseEvents() ([]*trace.Event, error) {
res, err := parseTrace()
if err != nil {
return nil, err
return res.Events, err
func parseTrace() (trace.ParseResult, error) {
loader.once.Do(func() {
tracef, err := os.Open(traceFile)
if err != nil {
loader.err = fmt.Errorf("failed to open trace file: %v", err)
defer tracef.Close()
// Parse and symbolize.
res, err := trace.Parse(bufio.NewReader(tracef), programBinary)
if err != nil {
loader.err = fmt.Errorf("failed to parse trace: %v", err)
loader.res = res
return loader.res, loader.err
// httpMain serves the starting page.
func httpMain(w http.ResponseWriter, r *http.Request) {
if err := templMain.Execute(w, ranges); err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
var templMain = template.Must(template.New("").Parse(`
{{if $}}
{{range $e := $}}
<a href="{{$e.URL}}">View trace ({{$e.Name}})</a><br>
<a href="/trace">View trace</a><br>
<a href="/goroutines">Goroutine analysis</a><br>
<a href="/io">Network blocking profile</a> (<a href="/io?raw=1" download="io.profile">⬇</a>)<br>
<a href="/block">Synchronization blocking profile</a> (<a href="/block?raw=1" download="block.profile">⬇</a>)<br>
<a href="/syscall">Syscall blocking profile</a> (<a href="/syscall?raw=1" download="syscall.profile">⬇</a>)<br>
<a href="/sched">Scheduler latency profile</a> (<a href="/sche?raw=1" download="sched.profile">⬇</a>)<br>
<a href="/usertasks">User-defined tasks</a><br>
<a href="/userregions">User-defined regions</a><br>
<a href="/mmu">Minimum mutator utilization</a><br>
func dief(msg string, args ...interface{}) {
fmt.Fprintf(os.Stderr, msg, args...)
var debugMemoryUsage bool
func init() {
v := os.Getenv("DEBUG_MEMORY_USAGE")
debugMemoryUsage = v != ""
func reportMemoryUsage(msg string) {
if !debugMemoryUsage {
var s runtime.MemStats
w := os.Stderr
fmt.Fprintf(w, "%s\n", msg)
fmt.Fprintf(w, " Alloc:\t%d Bytes\n", s.Alloc)
fmt.Fprintf(w, " Sys:\t%d Bytes\n", s.Sys)
fmt.Fprintf(w, " HeapReleased:\t%d Bytes\n", s.HeapReleased)
fmt.Fprintf(w, " HeapSys:\t%d Bytes\n", s.HeapSys)
fmt.Fprintf(w, " HeapInUse:\t%d Bytes\n", s.HeapInuse)
fmt.Fprintf(w, " HeapAlloc:\t%d Bytes\n", s.HeapAlloc)
var dummy string
fmt.Printf("Enter to continue...")
fmt.Scanf("%s", &dummy)