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tailscale/util/rands/cheap_test.go

197 lines
3.2 KiB
Go

// Copyright (c) Tailscale Inc & AUTHORS
// SPDX-License-Identifier: BSD-3-Clause
package rands
import (
"math/rand"
"sync"
"testing"
exprand "golang.org/x/exp/rand"
)
var (
seed uint64 = 8729831
numDraw = 100
numGoroutines = 5000
)
type workerPool struct {
job chan func()
res chan struct{}
wg sync.WaitGroup
}
func (p *workerPool) Close() {
close(p.job)
p.wg.Wait()
}
func newWorkerPool() *workerPool {
pool := workerPool{
job: make(chan func(), 2<<20),
res: make(chan struct{}, 2<<20),
wg: sync.WaitGroup{},
}
for i := 0; i < numGoroutines; i++ {
pool.wg.Add(1)
go func() {
defer pool.wg.Done()
for f := range pool.job {
f()
pool.res <- struct{}{}
}
}()
}
return &pool
}
var stdPool = sync.Pool{
New: func() any {
return rand.New(rand.NewSource(int64(seed)))
},
}
var expPool = sync.Pool{
New: func() any {
return exprand.New(exprand.NewSource(seed))
},
}
func BenchmarkStd(b *testing.B) {
pool := newWorkerPool()
defer pool.Close()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
pool.job <- func() {
rand.Seed(int64(seed))
for i := 0; i < numDraw; i++ {
rand.Intn(100)
}
}
}
for i := 0; i < b.N; i++ {
<-pool.res
}
}
func BenchmarkPCG(b *testing.B) {
pool := newWorkerPool()
defer pool.Close()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
pool.job <- func() {
exprand.Seed(seed)
for i := 0; i < numDraw; i++ {
exprand.Intn(100)
}
}
}
for i := 0; i < b.N; i++ {
<-pool.res
}
}
func BenchmarkStdPool(b *testing.B) {
pool := newWorkerPool()
defer pool.Close()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
pool.job <- func() {
r := stdPool.Get().(*rand.Rand)
defer stdPool.Put(r)
r.Seed(int64(seed))
for i := 0; i < numDraw; i++ {
r.Intn(100)
}
}
}
for i := 0; i < b.N; i++ {
<-pool.res
}
}
func BenchmarkPCGPool(b *testing.B) {
pool := newWorkerPool()
defer pool.Close()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
pool.job <- func() {
r := expPool.Get().(*exprand.Rand)
defer expPool.Put(r)
r.Seed(seed)
for i := 0; i < numDraw; i++ {
r.Intn(100)
}
}
}
for i := 0; i < b.N; i++ {
<-pool.res
}
}
func BenchmarkLocalStd(b *testing.B) {
pool := newWorkerPool()
defer pool.Close()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
pool.job <- func() {
r := rand.New(rand.NewSource(int64(seed)))
for i := 0; i < numDraw; i++ {
r.Intn(100)
}
}
}
for i := 0; i < b.N; i++ {
<-pool.res
}
}
func BenchmarkLocalPCG(b *testing.B) {
pool := newWorkerPool()
defer pool.Close()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
pool.job <- func() {
r := exprand.New(exprand.NewSource(seed))
for i := 0; i < numDraw; i++ {
r.Intn(100)
}
}
}
for i := 0; i < b.N; i++ {
<-pool.res
}
}
func BenchmarkStackRand(b *testing.B) {
pool := newWorkerPool()
defer pool.Close()
b.ReportAllocs()
for i := 0; i < b.N; i++ {
pool.job <- func() {
r := NewRand(seed)
for i := 0; i < numDraw; i++ {
r.Intn(100)
}
}
}
for i := 0; i < b.N; i++ {
<-pool.res
}
}
func TestStackRandNoAllocs(t *testing.T) {
seed := rand.Uint64()
if n := testing.AllocsPerRun(1000, func() {
r := NewRand(seed)
_ = r.Intn(100)
}); n > 0 {
t.Errorf("Rand got %v allocs per run", n)
}
}