Thomas
aa559bf496
Go is not cgroup aware and by default will set GOMAXPROCS to the number of available threads, regardless of whether it is within the allocated quota. This behaviour causes high amount of CPU throttling and degraded application performance.
122 lines
2.3 KiB
Go
122 lines
2.3 KiB
Go
// Copyright (C) 2016 The Syncthing Authors.
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//
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// This Source Code Form is subject to the terms of the Mozilla Public
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// License, v. 2.0. If a copy of the MPL was not distributed with this file,
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// You can obtain one at https://mozilla.org/MPL/2.0/.
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package main
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import (
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"flag"
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"fmt"
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"io"
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"log"
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"math/rand"
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"os"
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"path/filepath"
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"time"
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_ "go.uber.org/automaxprocs"
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)
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func main() {
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dir := flag.String("dir", "~/files", "Directory to generate into")
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files := flag.Int("files", 1000, "Number of files to create")
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maxExp := flag.Int("maxexp", 20, "Max size exponent")
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src := flag.String("src", "/dev/urandom", "Source of file data")
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flag.Parse()
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if err := generateFiles(*dir, *files, *maxExp, *src); err != nil {
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log.Println(err)
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}
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}
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func generateFiles(dir string, files, maxexp int, srcname string) error {
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fd, err := os.Open(srcname)
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if err != nil {
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return err
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}
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for i := 0; i < files; i++ {
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n := randomName()
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if rand.Float64() < 0.05 {
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// Some files and directories are dotfiles
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n = "." + n
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}
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p0 := filepath.Join(dir, string(n[0]), n[0:2])
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err = os.MkdirAll(p0, 0755)
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if err != nil {
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log.Fatal(err)
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}
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p1 := filepath.Join(p0, n)
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s := int64(1 << uint(rand.Intn(maxexp)))
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a := int64(128 * 1024)
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if a > s {
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a = s
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}
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s += rand.Int63n(a)
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if err := generateOneFile(fd, p1, s); err != nil {
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return err
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}
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}
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return nil
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}
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func generateOneFile(fd io.ReadSeeker, p1 string, s int64) error {
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src := io.LimitReader(&infiniteReader{fd}, s)
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dst, err := os.Create(p1)
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if err != nil {
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return err
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}
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_, err = io.Copy(dst, src)
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if err != nil {
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return err
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}
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err = dst.Close()
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if err != nil {
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return err
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}
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os.Chmod(p1, os.FileMode(rand.Intn(0777)|0400))
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t := time.Now().Add(-time.Duration(rand.Intn(30*86400)) * time.Second)
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return os.Chtimes(p1, t, t)
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}
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func randomName() string {
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var b [16]byte
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readRand(b[:])
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return fmt.Sprintf("%x", b[:])
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}
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func readRand(bs []byte) (int, error) {
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var r uint32
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for i := range bs {
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if i%4 == 0 {
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r = uint32(rand.Int63())
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}
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bs[i] = byte(r >> uint((i%4)*8))
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}
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return len(bs), nil
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}
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type infiniteReader struct {
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rd io.ReadSeeker
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}
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func (i *infiniteReader) Read(bs []byte) (int, error) {
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n, err := i.rd.Read(bs)
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if err == io.EOF {
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err = nil
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i.rd.Seek(0, 0)
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}
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return n, err
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}
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