syncPool_mem_usage_test

syncPool_mem_usage_test.go

package main

import (
	"fmt"
	"os"
	"runtime/pprof"
	"sync"
	"sync/atomic"
	"time"
)

var wg sync.WaitGroup
var newMake uint64
var reused uint64

var alloc int = 1e4

var bufPool = sync.Pool{
	New: func() interface{} {
		atomic.AddUint64(&newMake, 1)
		return make([]byte, 1e6)
	},
}

func main() {
	wg.Add(alloc)
	for i := 0; i < alloc; i++ {
		go func(num int) {
			// justMake()
			// bufPoolGet()
			bufPoolGetAndPut(num)
			// bufPoolSleepAndGetAndPut(num)
			wg.Done()
		}(i)
	}

	wg.Wait()

	// runtime.GC()
	// debug.FreeOSMemory()
	f, _ := os.Create("mem.porf")
	pprof.WriteHeapProfile(f)

	nm := newMake
	re := reused

	reSlice := [][]byte{}
	for i := 0; i < alloc; i++ {
		b := bufPool.Get()
		buf := b.([]byte)
		if buf[0] != 0 {
			fmt.Printf("reuse %s", buf)
			reSlice = append(reSlice, buf)
		}
	}

	println("newmake:", nm)
	println("reused:", re)
	println("reused slice(maybe equal to newmake) len:", len(reSlice))

}

func justMake() {
	buf := make([]byte, 1e6)
	atomic.AddUint64(&newMake, 1)
	if buf == nil {
		panic("never")
	}
}

func bufPoolGet(num ...int) []byte {
	buf := bufPool.Get()
	b := buf.([]byte)
	if b[0] != 0 {
		atomic.AddUint64(&reused, 1)
	} else {
		b = []byte(fmt.Sprintln(num))
	}
	return b
}

func bufPoolGetAndPut(num int) {
	b := bufPoolGet(num)
	bufPool.Put(b)
}

func bufPoolSleepAndGetAndPut(num int) {
	s := time.Duration(time.Now().UnixNano() % 5)
	time.Sleep(time.Millisecond * s)

	bufPoolGetAndPut(num)
}