blob: a685507c5e9b434ebb80e525ccd11bb7ab7e4aab [file] [log] [blame]
// 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.
// Garbage collection benchmark: parse Go packages repeatedly.
package main
import (
_ "net/http/pprof"
var serve = flag.String("serve", "", "serve http on this address at end")
func isGoFile(dir os.FileInfo) bool {
return !dir.IsDir() &&
!strings.HasPrefix(dir.Name(), ".") && // ignore .files
path.Ext(dir.Name()) == ".go"
func isPkgFile(dir os.FileInfo) bool {
return isGoFile(dir) &&
!strings.HasSuffix(dir.Name(), "_test.go") // ignore test files
func pkgName(filename string) string {
file, err := parser.ParseFile(token.NewFileSet(), filename, nil, parser.PackageClauseOnly)
if err != nil || file == nil {
return ""
return file.Name.Name
func parseDir(dirpath string) map[string]*ast.Package {
// the package name is the directory name within its parent
// (use dirname instead of path because dirname is clean; i.e. has no trailing '/')
_, pkgname := path.Split(dirpath)
// filter function to select the desired .go files
filter := func(d os.FileInfo) bool {
if isPkgFile(d) {
// Some directories contain main packages: Only accept
// files that belong to the expected package so that
// parser.ParsePackage doesn't return "multiple packages
// found" errors.
// Additionally, accept the special package name
// fakePkgName if we are looking at cmd documentation.
name := pkgName(dirpath + "/" + d.Name())
return name == pkgname
return false
// get package AST
pkgs, err := parser.ParseDir(token.NewFileSet(), dirpath, filter, parser.ParseComments)
if err != nil {
println("parse", dirpath, err.Error())
return pkgs
func main() {
st := new(runtime.MemStats)
packages = append(packages, packages...)
packages = append(packages, packages...)
n := flag.Int("n", 4, "iterations")
p := flag.Int("p", len(packages), "# of packages to keep in memory")
flag.BoolVar(&st.DebugGC, "d", st.DebugGC, "print GC debugging info (pause times)")
var lastParsed []map[string]*ast.Package
var t0 time.Time
var numGC uint32
var pauseTotalNs uint64
pkgroot := runtime.GOROOT() + "/src/"
for pass := 0; pass < 2; pass++ {
// Once the heap is grown to full size, reset counters.
// This hides the start-up pauses, which are much smaller
// than the normal pauses and would otherwise make
// the average look much better than it actually is.
numGC = st.NumGC
pauseTotalNs = st.PauseTotalNs
t0 = time.Now()
for i := 0; i < *n; i++ {
parsed := make([]map[string]*ast.Package, *p)
for j := range parsed {
parsed[j] = parseDir(pkgroot + packages[j%len(packages)])
if i+1 == *n && *serve != "" {
lastParsed = parsed
t1 := time.Now()
st.NumGC -= numGC
st.PauseTotalNs -= pauseTotalNs
fmt.Printf("Alloc=%d/%d Heap=%d Mallocs=%d PauseTime=%.3f/%d = %.3f\n",
st.Alloc, st.TotalAlloc,
st.Mallocs, float64(st.PauseTotalNs)/1e9,
st.NumGC, float64(st.PauseTotalNs)/1e9/float64(st.NumGC))
fmt.Printf("%10s %10s %10s\n", "size", "#alloc", "#free")
for _, s := range st.BySize {
fmt.Printf("%10d %10d %10d\n", s.Size, s.Mallocs, s.Frees)
// Standard gotest benchmark output, collected by build dashboard.
gcstats("BenchmarkParser", *n, t1.Sub(t0))
if *serve != "" {
log.Fatal(http.ListenAndServe(*serve, nil))
// find . -type d -not -path "./exp" -not -path "./exp/*" -printf "\t\"%p\",\n" | sort | sed "s/\.\///" | grep -v testdata
var packages = []string{