libgo/go/http/pprof/pprof.go

   1 // Copyright 2010 The Go Authors.  All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // Package pprof serves via its HTTP server runtime profiling data
   6 // in the format expected by the pprof visualization tool.
   7 // For more information about pprof, see
   8 // http://code.google.com/p/google-perftools/.
   9 //
  10 // The package is typically only imported for the side effect of
  11 // registering its HTTP handlers.
  12 // The handled paths all begin with /debug/pprof/.
  13 //
  14 // To use pprof, link this package into your program:
  15 //      import _ "http/pprof"
  16 //
  17 // Then use the pprof tool to look at the heap profile:
  18 //
  19 //      pprof http://localhost:6060/debug/pprof/heap
  20 //
  21 package pprof
  22
  23 import (
  24         "bufio"
  25         "fmt"
  26         "http"
  27         "os"
  28         "runtime"
  29         "runtime/pprof"
  30         "strconv"
  31         "strings"
  32 )
  33
  34 func init() {
  35         http.Handle("/debug/pprof/cmdline", http.HandlerFunc(Cmdline))
  36         http.Handle("/debug/pprof/heap", http.HandlerFunc(Heap))
  37         http.Handle("/debug/pprof/symbol", http.HandlerFunc(Symbol))
  38 }
  39
  40 // Cmdline responds with the running program's
  41 // command line, with arguments separated by NUL bytes.
  42 // The package initialization registers it as /debug/pprof/cmdline.
  43 func Cmdline(w http.ResponseWriter, r *http.Request) {
  44         w.SetHeader("content-type", "text/plain; charset=utf-8")
  45         fmt.Fprintf(w, strings.Join(os.Args, "\x00"))
  46 }
  47
  48 // Heap responds with the pprof-formatted heap profile.
  49 // The package initialization registers it as /debug/pprof/heap.
  50 func Heap(w http.ResponseWriter, r *http.Request) {
  51         w.SetHeader("content-type", "text/plain; charset=utf-8")
  52         pprof.WriteHeapProfile(w)
  53 }
  54
  55 // Symbol looks up the program counters listed in the request,
  56 // responding with a table mapping program counters to function names.
  57 // The package initialization registers it as /debug/pprof/symbol.
  58 func Symbol(w http.ResponseWriter, r *http.Request) {
  59         w.SetHeader("content-type", "text/plain; charset=utf-8")
  60
  61         // We don't know how many symbols we have, but we
  62         // do have symbol information.  Pprof only cares whether
  63         // this number is 0 (no symbols available) or > 0.
  64         fmt.Fprintf(w, "num_symbols: 1\n")
  65
  66         var b *bufio.Reader
  67         if r.Method == "POST" {
  68                 b = bufio.NewReader(r.Body)
  69         } else {
  70                 b = bufio.NewReader(strings.NewReader(r.URL.RawQuery))
  71         }
  72
  73         for {
  74                 word, err := b.ReadSlice('+')
  75                 if err == nil {
  76                         word = word[0 : len(word)-1] // trim +
  77                 }
  78                 pc, _ := strconv.Btoui64(string(word), 0)
  79                 if pc != 0 {
  80                         f := runtime.FuncForPC(uintptr(pc))
  81                         if f != nil {
  82                                 fmt.Fprintf(w, "%#x %s\n", pc, f.Name())
  83                         }
  84                 }
  85
  86                 // Wait until here to check for err; the last
  87                 // symbol will have an err because it doesn't end in +.
  88                 if err != nil {
  89                         break
  90                 }
  91         }
  92 }