cmd/trace: add new command

Trace command allows to visualize and analyze traces.
Run as:
$ go tool trace binary trace.file
The commands opens web browser with the main page,
which contains links for trace visualization,
blocking profiler, network IO profiler and per-goroutine
traces.

Also move trace parser from runtime/pprof/trace_parser_test.go
to internal/trace/parser.go, so that it can be shared between
tests and the command.

Change-Id: Ic97ed59ad6e4c7e1dc9eca5e979701a2b4aed7cf
Reviewed-on: https://go-review.googlesource.com/3601
Reviewed-by: Andrew Gerrand <adg@golang.org>

src/cmd/trace/pprof.go

@@ -0,0 +1,162 @@
+// 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.
+
+// Serving of pprof-like profiles.
+
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"internal/trace"
+	"io/ioutil"
+	"net/http"
+	"os"
+	"os/exec"
+)
+
+func init() {
+	http.HandleFunc("/io", httpIO)
+	http.HandleFunc("/block", httpBlock)
+	http.HandleFunc("/syscall", httpSyscall)
+	http.HandleFunc("/sched", httpSched)
+}
+
+// Record represents one entry in pprof-like profiles.
+type Record struct {
+	stk  []*trace.Frame
+	n    uint64
+	time int64
+}
+
+// httpIO serves IO pprof-like profile (time spent in IO wait).
+func httpIO(w http.ResponseWriter, r *http.Request) {
+	events, err := parseEvents()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	prof := make(map[uint64]Record)
+	for _, ev := range events {
+		if ev.Type != trace.EvGoBlockNet || ev.Link == nil || ev.StkID == 0 || len(ev.Stk) == 0 {
+			continue
+		}
+		rec := prof[ev.StkID]
+		rec.stk = ev.Stk
+		rec.n++
+		rec.time += ev.Link.Ts - ev.Ts
+		prof[ev.StkID] = rec
+	}
+	serveSVGProfile(w, r, prof)
+}
+
+// httpBlock serves blocking pprof-like profile (time spent blocked on synchronization primitives).
+func httpBlock(w http.ResponseWriter, r *http.Request) {
+	events, err := parseEvents()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	prof := make(map[uint64]Record)
+	for _, ev := range events {
+		switch ev.Type {
+		case trace.EvGoBlockSend, trace.EvGoBlockRecv, trace.EvGoBlockSelect,
+			trace.EvGoBlockSync, trace.EvGoBlockCond:
+		default:
+			continue
+		}
+		if ev.Link == nil || ev.StkID == 0 || len(ev.Stk) == 0 {
+			continue
+		}
+		rec := prof[ev.StkID]
+		rec.stk = ev.Stk
+		rec.n++
+		rec.time += ev.Link.Ts - ev.Ts
+		prof[ev.StkID] = rec
+	}
+	serveSVGProfile(w, r, prof)
+}
+
+// httpSyscall serves syscall pprof-like profile (time spent blocked in syscalls).
+func httpSyscall(w http.ResponseWriter, r *http.Request) {
+	events, err := parseEvents()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	prof := make(map[uint64]Record)
+	for _, ev := range events {
+		if ev.Type != trace.EvGoSysCall || ev.Link == nil || ev.StkID == 0 || len(ev.Stk) == 0 {
+			continue
+		}
+		rec := prof[ev.StkID]
+		rec.stk = ev.Stk
+		rec.n++
+		rec.time += ev.Link.Ts - ev.Ts
+		prof[ev.StkID] = rec
+	}
+	serveSVGProfile(w, r, prof)
+}
+
+// httpSched serves scheduler latency pprof-like profile
+// (time between a goroutine become runnable and actually scheduled for execution).
+func httpSched(w http.ResponseWriter, r *http.Request) {
+	events, err := parseEvents()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	prof := make(map[uint64]Record)
+	for _, ev := range events {
+		if (ev.Type != trace.EvGoUnblock && ev.Type != trace.EvGoCreate) ||
+			ev.Link == nil || ev.StkID == 0 || len(ev.Stk) == 0 {
+			continue
+		}
+		rec := prof[ev.StkID]
+		rec.stk = ev.Stk
+		rec.n++
+		rec.time += ev.Link.Ts - ev.Ts
+		prof[ev.StkID] = rec
+	}
+	serveSVGProfile(w, r, prof)
+}
+
+// generateSVGProfile generates pprof-like profile stored in prof and writes in to w.
+func serveSVGProfile(w http.ResponseWriter, r *http.Request, prof map[uint64]Record) {
+	blockf, err := ioutil.TempFile("", "block")
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to create temp file: %v", err), http.StatusInternalServerError)
+		return
+	}
+	defer os.Remove(blockf.Name())
+	blockb := bufio.NewWriter(blockf)
+	fmt.Fprintf(blockb, "--- contention:\ncycles/second=1000000000\n")
+	for _, rec := range prof {
+		fmt.Fprintf(blockb, "%v %v @", rec.time, rec.n)
+		for _, f := range rec.stk {
+			fmt.Fprintf(blockb, " 0x%x", f.PC)
+		}
+		fmt.Fprintf(blockb, "\n")
+	}
+	err = blockb.Flush()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to flush temp file: %v", err), http.StatusInternalServerError)
+		return
+	}
+	err = blockf.Close()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to close temp file: %v", err), http.StatusInternalServerError)
+		return
+	}
+
+	svgFilename := blockf.Name() + ".svg"
+	_, err = exec.Command("go", "tool", "pprof", "-svg", "-output", svgFilename, programBinary, blockf.Name()).CombinedOutput()
+	if err != nil {
+		http.Error(w, fmt.Sprintf("failed to execute go tool pprof: %v", err), http.StatusInternalServerError)
+		return
+	}
+	defer os.Remove(svgFilename)
+	w.Header().Set("Content-Type", "image/svg+xml")
+	http.ServeFile(w, r, svgFilename)
+}