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// Copyright 2010 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 pprof serves via its HTTP server runtime profiling data
// in the format expected by the pprof visualization tool.
// For more information about pprof, see
// http://code.google.com/p/google-perftools/.
//
// The package is typically only imported for the side effect of
// registering its HTTP handlers.
// The handled paths all begin with /debug/pprof/.
//
// To use pprof, link this package into your program:
// import _ "http/pprof"
//
// Then use the pprof tool to look at the heap profile:
//
// pprof http://localhost:6060/debug/pprof/heap
//
// Or to look at a 30-second CPU profile:
//
// pprof http://localhost:6060/debug/pprof/profile
//
package pprof
import (
"bufio"
"bytes"
"fmt"
"http"
"io"
"os"
"runtime"
"runtime/pprof"
"strconv"
"strings"
"time"
)
func init() {
http.Handle("/debug/pprof/cmdline", http.HandlerFunc(Cmdline))
http.Handle("/debug/pprof/profile", http.HandlerFunc(Profile))
http.Handle("/debug/pprof/heap", http.HandlerFunc(Heap))
http.Handle("/debug/pprof/symbol", http.HandlerFunc(Symbol))
}
// Cmdline responds with the running program's
// command line, with arguments separated by NUL bytes.
// The package initialization registers it as /debug/pprof/cmdline.
func Cmdline(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
fmt.Fprintf(w, strings.Join(os.Args, "\x00"))
}
// Heap responds with the pprof-formatted heap profile.
// The package initialization registers it as /debug/pprof/heap.
func Heap(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
pprof.WriteHeapProfile(w)
}
// Profile responds with the pprof-formatted cpu profile.
// The package initialization registers it as /debug/pprof/profile.
func Profile(w http.ResponseWriter, r *http.Request) {
sec, _ := strconv.Atoi64(r.FormValue("seconds"))
if sec == 0 {
sec = 30
}
// Set Content Type assuming StartCPUProfile will work,
// because if it does it starts writing.
w.Header().Set("Content-Type", "application/octet-stream")
if err := pprof.StartCPUProfile(w); err != nil {
// StartCPUProfile failed, so no writes yet.
// Can change header back to text content
// and send error code.
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
w.WriteHeader(http.StatusInternalServerError)
fmt.Fprintf(w, "Could not enable CPU profiling: %s\n", err)
return
}
time.Sleep(sec * 1e9)
pprof.StopCPUProfile()
}
// Symbol looks up the program counters listed in the request,
// responding with a table mapping program counters to function names.
// The package initialization registers it as /debug/pprof/symbol.
func Symbol(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Content-Type", "text/plain; charset=utf-8")
// We have to read the whole POST body before
// writing any output. Buffer the output here.
var buf bytes.Buffer
// We don't know how many symbols we have, but we
// do have symbol information. Pprof only cares whether
// this number is 0 (no symbols available) or > 0.
fmt.Fprintf(&buf, "num_symbols: 1\n")
var b *bufio.Reader
if r.Method == "POST" {
b = bufio.NewReader(r.Body)
} else {
b = bufio.NewReader(strings.NewReader(r.URL.RawQuery))
}
for {
word, err := b.ReadSlice('+')
if err == nil {
word = word[0 : len(word)-1] // trim +
}
pc, _ := strconv.Btoui64(string(word), 0)
if pc != 0 {
f := runtime.FuncForPC(uintptr(pc))
if f != nil {
fmt.Fprintf(&buf, "%#x %s\n", pc, f.Name())
}
}
// Wait until here to check for err; the last
// symbol will have an err because it doesn't end in +.
if err != nil {
if err != io.EOF {
fmt.Fprintf(&buf, "reading request: %v\n", err)
}
break
}
}
w.Write(buf.Bytes())
}
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