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// Copyright 2015 Marc-Antoine Ruel. All rights reserved.
// Use of this source code is governed under the Apache License, Version 2.0
// that can be found in the LICENSE file.
// Package stack analyzes stack dump of Go processes and simplifies it.
//
// It is mostly useful on servers will large number of identical goroutines,
// making the crash dump harder to read than strictly necessary.
package stack
import (
"fmt"
"math"
"net/url"
"os"
"path/filepath"
"sort"
"strings"
"unicode"
"unicode/utf8"
)
// Func is a function call.
//
// Go stack traces print a mangled function call, this wrapper unmangle the
// string before printing and adds other filtering methods.
type Func struct {
Raw string
}
// String is the fully qualified function name.
//
// Sadly Go is a bit confused when the package name doesn't match the directory
// containing the source file and will use the directory name instead of the
// real package name.
func (f *Func) String() string {
s, _ := url.QueryUnescape(f.Raw)
return s
}
// Name is the naked function name.
func (f *Func) Name() string {
parts := strings.SplitN(filepath.Base(f.Raw), ".", 2)
if len(parts) == 1 {
return parts[0]
}
return parts[1]
}
// PkgName is the package name for this function reference.
func (f *Func) PkgName() string {
parts := strings.SplitN(filepath.Base(f.Raw), ".", 2)
if len(parts) == 1 {
return ""
}
s, _ := url.QueryUnescape(parts[0])
return s
}
// PkgDotName returns "<package>.<func>" format.
func (f *Func) PkgDotName() string {
parts := strings.SplitN(filepath.Base(f.Raw), ".", 2)
s, _ := url.QueryUnescape(parts[0])
if len(parts) == 1 {
return parts[0]
}
if s != "" || parts[1] != "" {
return s + "." + parts[1]
}
return ""
}
// IsExported returns true if the function is exported.
func (f *Func) IsExported() bool {
name := f.Name()
parts := strings.Split(name, ".")
r, _ := utf8.DecodeRuneInString(parts[len(parts)-1])
if unicode.ToUpper(r) == r {
return true
}
return f.PkgName() == "main" && name == "main"
}
// Arg is an argument on a Call.
type Arg struct {
Value uint64 // Value is the raw value as found in the stack trace
Name string // Name is a pseudo name given to the argument
}
// IsPtr returns true if we guess it's a pointer. It's only a guess, it can be
// easily be confused by a bitmask.
func (a *Arg) IsPtr() bool {
// Assumes all pointers are above 16Mb and positive.
return a.Value > 16*1024*1024 && a.Value < math.MaxInt64
}
func (a *Arg) String() string {
if a.Name != "" {
return a.Name
}
if a.Value == 0 {
return "0"
}
return fmt.Sprintf("0x%x", a.Value)
}
// Args is a series of function call arguments.
type Args struct {
Values []Arg // Values is the arguments as shown on the stack trace. They are mangled via simplification.
Processed []string // Processed is the arguments generated from processing the source files. It can have a length lower than Values.
Elided bool // If set, it means there was a trailing ", ..."
}
func (a *Args) String() string {
var v []string
if len(a.Processed) != 0 {
v = make([]string, 0, len(a.Processed))
for _, item := range a.Processed {
v = append(v, item)
}
} else {
v = make([]string, 0, len(a.Values))
for _, item := range a.Values {
v = append(v, item.String())
}
}
if a.Elided {
v = append(v, "...")
}
return strings.Join(v, ", ")
}
// equal returns true only if both arguments are exactly equal.
func (a *Args) equal(r *Args) bool {
if a.Elided != r.Elided || len(a.Values) != len(r.Values) {
return false
}
for i, l := range a.Values {
if l != r.Values[i] {
return false
}
}
return true
}
// similar returns true if the two Args are equal or almost but not quite
// equal.
func (a *Args) similar(r *Args, similar Similarity) bool {
if a.Elided != r.Elided || len(a.Values) != len(r.Values) {
return false
}
if similar == AnyValue {
return true
}
for i, l := range a.Values {
switch similar {
case ExactFlags, ExactLines:
if l != r.Values[i] {
return false
}
default:
if l.IsPtr() != r.Values[i].IsPtr() || (!l.IsPtr() && l != r.Values[i]) {
return false
}
}
}
return true
}
// merge merges two similar Args, zapping out differences.
func (a *Args) merge(r *Args) Args {
out := Args{
Values: make([]Arg, len(a.Values)),
Elided: a.Elided,
}
for i, l := range a.Values {
if l != r.Values[i] {
out.Values[i].Name = "*"
out.Values[i].Value = l.Value
} else {
out.Values[i] = l
}
}
return out
}
// Call is an item in the stack trace.
type Call struct {
SrcPath string // Full path name of the source file as seen in the trace
LocalSrcPath string // Full path name of the source file as seen in the host.
Line int // Line number
Func Func // Fully qualified function name (encoded).
Args Args // Call arguments
IsStdlib bool // true if it is a Go standard library function. This includes the 'go test' generated main executable.
}
// equal returns true only if both calls are exactly equal.
func (c *Call) equal(r *Call) bool {
return c.SrcPath == r.SrcPath && c.Line == r.Line && c.Func == r.Func && c.Args.equal(&r.Args)
}
// similar returns true if the two Call are equal or almost but not quite
// equal.
func (c *Call) similar(r *Call, similar Similarity) bool {
return c.SrcPath == r.SrcPath && c.Line == r.Line && c.Func == r.Func && c.Args.similar(&r.Args, similar)
}
// merge merges two similar Call, zapping out differences.
func (c *Call) merge(r *Call) Call {
return Call{
SrcPath: c.SrcPath,
Line: c.Line,
Func: c.Func,
Args: c.Args.merge(&r.Args),
LocalSrcPath: c.LocalSrcPath,
IsStdlib: c.IsStdlib,
}
}
// SrcName returns the base file name of the source file.
func (c *Call) SrcName() string {
return filepath.Base(c.SrcPath)
}
// SrcLine returns "source.go:line", including only the base file name.
func (c *Call) SrcLine() string {
return fmt.Sprintf("%s:%d", c.SrcName(), c.Line)
}
// FullSrcLine returns "/path/to/source.go:line".
//
// This file path is mutated to look like the local path.
func (c *Call) FullSrcLine() string {
return fmt.Sprintf("%s:%d", c.SrcPath, c.Line)
}
// PkgSrc is one directory plus the file name of the source file.
func (c *Call) PkgSrc() string {
return filepath.Join(filepath.Base(filepath.Dir(c.SrcPath)), c.SrcName())
}
// IsPkgMain returns true if it is in the main package.
func (c *Call) IsPkgMain() bool {
return c.Func.PkgName() == "main"
}
const testMainSrc = "_test" + string(os.PathSeparator) + "_testmain.go"
// updateLocations initializes LocalSrcPath and IsStdlib.
func (c *Call) updateLocations(goroot, localgoroot string, gopaths map[string]string) {
if c.SrcPath != "" {
// Always check GOROOT first, then GOPATH.
if strings.HasPrefix(c.SrcPath, goroot) {
// Replace remote GOROOT with local GOROOT.
c.LocalSrcPath = filepath.Join(localgoroot, c.SrcPath[len(goroot):])
} else {
// Replace remote GOPATH with local GOPATH.
c.LocalSrcPath = c.SrcPath
// TODO(maruel): Sort for deterministic behavior?
for prefix, dest := range gopaths {
if strings.HasPrefix(c.SrcPath, prefix) {
c.LocalSrcPath = filepath.Join(dest, c.SrcPath[len(prefix):])
break
}
}
}
}
// Consider _test/_testmain.go as stdlib since it's injected by "go test".
c.IsStdlib = (goroot != "" && strings.HasPrefix(c.SrcPath, goroot)) || c.PkgSrc() == testMainSrc
}
// Stack is a call stack.
type Stack struct {
Calls []Call // Call stack. First is original function, last is leaf function.
Elided bool // Happens when there's >100 items in Stack, currently hardcoded in package runtime.
}
// equal returns true on if both call stacks are exactly equal.
func (s *Stack) equal(r *Stack) bool {
if len(s.Calls) != len(r.Calls) || s.Elided != r.Elided {
return false
}
for i := range s.Calls {
if !s.Calls[i].equal(&r.Calls[i]) {
return false
}
}
return true
}
// similar returns true if the two Stack are equal or almost but not quite
// equal.
func (s *Stack) similar(r *Stack, similar Similarity) bool {
if len(s.Calls) != len(r.Calls) || s.Elided != r.Elided {
return false
}
for i := range s.Calls {
if !s.Calls[i].similar(&r.Calls[i], similar) {
return false
}
}
return true
}
// merge merges two similar Stack, zapping out differences.
func (s *Stack) merge(r *Stack) *Stack {
// Assumes similar stacks have the same length.
out := &Stack{
Calls: make([]Call, len(s.Calls)),
Elided: s.Elided,
}
for i := range s.Calls {
out.Calls[i] = s.Calls[i].merge(&r.Calls[i])
}
return out
}
// less compares two Stack, where the ones that are less are more
// important, so they come up front.
//
// A Stack with more private functions is 'less' so it is at the top.
// Inversely, a Stack with only public functions is 'more' so it is at the
// bottom.
func (s *Stack) less(r *Stack) bool {
lStdlib := 0
lPrivate := 0
for _, c := range s.Calls {
if c.IsStdlib {
lStdlib++
} else {
lPrivate++
}
}
rStdlib := 0
rPrivate := 0
for _, s := range r.Calls {
if s.IsStdlib {
rStdlib++
} else {
rPrivate++
}
}
if lPrivate > rPrivate {
return true
}
if lPrivate < rPrivate {
return false
}
if lStdlib > rStdlib {
return false
}
if lStdlib < rStdlib {
return true
}
// Stack lengths are the same.
for x := range s.Calls {
if s.Calls[x].Func.Raw < r.Calls[x].Func.Raw {
return true
}
if s.Calls[x].Func.Raw > r.Calls[x].Func.Raw {
return true
}
if s.Calls[x].PkgSrc() < r.Calls[x].PkgSrc() {
return true
}
if s.Calls[x].PkgSrc() > r.Calls[x].PkgSrc() {
return true
}
if s.Calls[x].Line < r.Calls[x].Line {
return true
}
if s.Calls[x].Line > r.Calls[x].Line {
return true
}
}
return false
}
func (s *Stack) updateLocations(goroot, localgoroot string, gopaths map[string]string) {
for i := range s.Calls {
s.Calls[i].updateLocations(goroot, localgoroot, gopaths)
}
}
// Signature represents the signature of one or multiple goroutines.
//
// It is effectively the stack trace plus the goroutine internal bits, like
// it's state, if it is thread locked, which call site created this goroutine,
// etc.
type Signature struct {
// Use git grep 'gopark(|unlock)\(' to find them all plus everything listed
// in runtime/traceback.go. Valid values includes:
// - chan send, chan receive, select
// - finalizer wait, mark wait (idle),
// - Concurrent GC wait, GC sweep wait, force gc (idle)
// - IO wait, panicwait
// - semacquire, semarelease
// - sleep, timer goroutine (idle)
// - trace reader (blocked)
// Stuck cases:
// - chan send (nil chan), chan receive (nil chan), select (no cases)
// Runnable states:
// - idle, runnable, running, syscall, waiting, dead, enqueue, copystack,
// Scan states:
// - scan, scanrunnable, scanrunning, scansyscall, scanwaiting, scandead,
// scanenqueue
State string
CreatedBy Call // Which other goroutine which created this one.
SleepMin int // Wait time in minutes, if applicable.
SleepMax int // Wait time in minutes, if applicable.
Stack Stack
Locked bool // Locked to an OS thread.
}
// equal returns true only if both signatures are exactly equal.
func (s *Signature) equal(r *Signature) bool {
if s.State != r.State || !s.CreatedBy.equal(&r.CreatedBy) || s.Locked != r.Locked || s.SleepMin != r.SleepMin || s.SleepMax != r.SleepMax {
return false
}
return s.Stack.equal(&r.Stack)
}
// similar returns true if the two Signature are equal or almost but not quite
// equal.
func (s *Signature) similar(r *Signature, similar Similarity) bool {
if s.State != r.State || !s.CreatedBy.similar(&r.CreatedBy, similar) {
return false
}
if similar == ExactFlags && s.Locked != r.Locked {
return false
}
return s.Stack.similar(&r.Stack, similar)
}
// merge merges two similar Signature, zapping out differences.
func (s *Signature) merge(r *Signature) *Signature {
min := s.SleepMin
if r.SleepMin < min {
min = r.SleepMin
}
max := s.SleepMax
if r.SleepMax > max {
max = r.SleepMax
}
return &Signature{
State: s.State, // Drop right side.
CreatedBy: s.CreatedBy, // Drop right side.
SleepMin: min,
SleepMax: max,
Stack: *s.Stack.merge(&r.Stack),
Locked: s.Locked || r.Locked, // TODO(maruel): This is weirdo.
}
}
// less compares two Signature, where the ones that are less are more
// important, so they come up front. A Signature with more private functions is
// 'less' so it is at the top. Inversely, a Signature with only public
// functions is 'more' so it is at the bottom.
func (s *Signature) less(r *Signature) bool {
if s.Stack.less(&r.Stack) {
return true
}
if r.Stack.less(&s.Stack) {
return false
}
if s.Locked && !r.Locked {
return true
}
if r.Locked && !s.Locked {
return false
}
if s.State < r.State {
return true
}
if s.State > r.State {
return false
}
return false
}
// SleepString returns a string "N-M minutes" if the goroutine(s) slept for a
// long time.
//
// Returns an empty string otherwise.
func (s *Signature) SleepString() string {
if s.SleepMax == 0 {
return ""
}
if s.SleepMin != s.SleepMax {
return fmt.Sprintf("%d~%d minutes", s.SleepMin, s.SleepMax)
}
return fmt.Sprintf("%d minutes", s.SleepMax)
}
// CreatedByString return a short context about the origin of this goroutine
// signature.
func (s *Signature) CreatedByString(fullPath bool) string {
created := s.CreatedBy.Func.PkgDotName()
if created == "" {
return ""
}
created += " @ "
if fullPath {
created += s.CreatedBy.FullSrcLine()
} else {
created += s.CreatedBy.SrcLine()
}
return created
}
func (s *Signature) updateLocations(goroot, localgoroot string, gopaths map[string]string) {
s.CreatedBy.updateLocations(goroot, localgoroot, gopaths)
s.Stack.updateLocations(goroot, localgoroot, gopaths)
}
// Goroutine represents the state of one goroutine, including the stack trace.
type Goroutine struct {
Signature // It's stack trace, internal bits, state, which call site created it, etc.
ID int // Goroutine ID.
First bool // First is the goroutine first printed, normally the one that crashed.
}
// Private stuff.
// nameArguments is a post-processing step where Args are 'named' with numbers.
func nameArguments(goroutines []*Goroutine) {
// Set a name for any pointer occurring more than once.
type object struct {
args []*Arg
inPrimary bool
id int
}
objects := map[uint64]object{}
// Enumerate all the arguments.
for i := range goroutines {
for j := range goroutines[i].Stack.Calls {
for k := range goroutines[i].Stack.Calls[j].Args.Values {
arg := goroutines[i].Stack.Calls[j].Args.Values[k]
if arg.IsPtr() {
objects[arg.Value] = object{
args: append(objects[arg.Value].args, &goroutines[i].Stack.Calls[j].Args.Values[k]),
inPrimary: objects[arg.Value].inPrimary || i == 0,
}
}
}
}
// CreatedBy.Args is never set.
}
order := make(uint64Slice, 0, len(objects)/2)
for k, obj := range objects {
if len(obj.args) > 1 && obj.inPrimary {
order = append(order, k)
}
}
sort.Sort(order)
nextID := 1
for _, k := range order {
for _, arg := range objects[k].args {
arg.Name = fmt.Sprintf("#%d", nextID)
}
nextID++
}
// Now do the rest. This is done so the output is deterministic.
order = make(uint64Slice, 0, len(objects))
for k := range objects {
order = append(order, k)
}
sort.Sort(order)
for _, k := range order {
// Process the remaining pointers, they were not referenced by primary
// thread so will have higher IDs.
if objects[k].inPrimary {
continue
}
for _, arg := range objects[k].args {
arg.Name = fmt.Sprintf("#%d", nextID)
}
nextID++
}
}
type uint64Slice []uint64
func (a uint64Slice) Len() int { return len(a) }
func (a uint64Slice) Swap(i, j int) { a[i], a[j] = a[j], a[i] }
func (a uint64Slice) Less(i, j int) bool { return a[i] < a[j] }
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