196 lines
5 KiB
Go
196 lines
5 KiB
Go
// Package profile provides a simple way to manage runtime/pprof
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// profiling of your Go application.
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package profile
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import (
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"io/ioutil"
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"log"
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"os"
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"os/signal"
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"path/filepath"
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"runtime"
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"runtime/pprof"
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"sync/atomic"
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)
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// started counts the number of times Start has been called
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var started uint32
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const (
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cpuMode = iota
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memMode
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blockMode
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)
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type profile struct {
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// quiet suppresses informational messages during profiling.
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quiet bool
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// noShutdownHook controls whether the profiling package should
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// hook SIGINT to write profiles cleanly.
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noShutdownHook bool
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// mode holds the type of profiling that will be made
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mode int
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// path holds the base path where various profiling files are written.
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// If blank, the base path will be generated by ioutil.TempDir.
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path string
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// memProfileRate holds the rate for the memory profile.
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memProfileRate int
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// closers holds the cleanup functions that run after each profile
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closers []func()
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// stopped records if a call to profile.Stop has been made
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stopped uint32
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}
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// NoShutdownHook controls whether the profiling package should
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// hook SIGINT to write profiles cleanly.
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// Programs with more sophisticated signal handling should set
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// this to true and ensure the Stop() function returned from Start()
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// is called during shutdown.
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func NoShutdownHook(p *profile) { p.noShutdownHook = true }
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// Quiet suppresses informational messages during profiling.
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func Quiet(p *profile) { p.quiet = true }
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// CPUProfile controls if cpu profiling will be enabled. It disables any previous profiling settings.
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func CPUProfile(p *profile) { p.mode = cpuMode }
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// DefaultMemProfileRate is the default memory profiling rate.
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// See also http://golang.org/pkg/runtime/#pkg-variables
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const DefaultMemProfileRate = 4096
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// MemProfile controls if memory profiling will be enabled. It disables any previous profiling settings.
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func MemProfile(p *profile) {
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p.memProfileRate = DefaultMemProfileRate
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p.mode = memMode
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}
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// MemProfileRate controls if memory profiling will be enabled. Additionally, it takes a parameter which
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// allows the setting of the memory profile rate.
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func MemProfileRate(rate int) func(*profile) {
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return func(p *profile) {
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p.memProfileRate = rate
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p.mode = memMode
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}
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}
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// BlockProfile controls if block (contention) profiling will be enabled. It disables any previous profiling settings.
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func BlockProfile(p *profile) { p.mode = blockMode }
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// ProfilePath controls the base path where various profiling
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// files are written. If blank, the base path will be generated
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// by ioutil.TempDir.
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func ProfilePath(path string) func(*profile) {
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return func(p *profile) {
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p.path = path
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}
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}
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// Stop stops the profile and flushes any unwritten data.
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func (p *profile) Stop() {
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if !atomic.CompareAndSwapUint32(&p.stopped, 0, 1) {
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// someone has already called close
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return
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}
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for _, c := range p.closers {
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c()
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}
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}
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// Start starts a new profiling session.
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// The caller should call the Stop method on the value returned
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// to cleanly stop profiling. Start can only be called once
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// per program execution.
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func Start(options ...func(*profile)) interface {
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Stop()
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} {
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if !atomic.CompareAndSwapUint32(&started, 0, 1) {
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log.Fatal("profile: Start() already called")
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}
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var prof profile
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for _, option := range options {
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option(&prof)
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}
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path, err := func() (string, error) {
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if p := prof.path; p != "" {
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return p, os.MkdirAll(p, 0777)
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}
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return ioutil.TempDir("", "profile")
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}()
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if err != nil {
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log.Fatalf("profile: could not create initial output directory: %v", err)
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}
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switch prof.mode {
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case cpuMode:
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fn := filepath.Join(path, "cpu.pprof")
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f, err := os.Create(fn)
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if err != nil {
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log.Fatalf("profile: could not create cpu profile %q: %v", fn, err)
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}
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if !prof.quiet {
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log.Printf("profile: cpu profiling enabled, %s", fn)
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}
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pprof.StartCPUProfile(f)
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prof.closers = append(prof.closers, func() {
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pprof.StopCPUProfile()
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f.Close()
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})
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case memMode:
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fn := filepath.Join(path, "mem.pprof")
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f, err := os.Create(fn)
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if err != nil {
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log.Fatalf("profile: could not create memory profile %q: %v", fn, err)
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}
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old := runtime.MemProfileRate
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runtime.MemProfileRate = prof.memProfileRate
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if !prof.quiet {
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log.Printf("profile: memory profiling enabled (rate %d), %s", runtime.MemProfileRate, fn)
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}
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prof.closers = append(prof.closers, func() {
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pprof.Lookup("heap").WriteTo(f, 0)
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f.Close()
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runtime.MemProfileRate = old
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})
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case blockMode:
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fn := filepath.Join(path, "block.pprof")
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f, err := os.Create(fn)
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if err != nil {
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log.Fatalf("profile: could not create block profile %q: %v", fn, err)
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}
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runtime.SetBlockProfileRate(1)
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if !prof.quiet {
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log.Printf("profile: block profiling enabled, %s", fn)
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}
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prof.closers = append(prof.closers, func() {
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pprof.Lookup("block").WriteTo(f, 0)
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f.Close()
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runtime.SetBlockProfileRate(0)
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})
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}
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if !prof.noShutdownHook {
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go func() {
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c := make(chan os.Signal, 1)
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signal.Notify(c, os.Interrupt)
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<-c
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log.Println("profile: caught interrupt, stopping profiles")
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prof.Stop()
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os.Exit(0)
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}()
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}
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return &prof
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}
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