github.com/qiuhoude/go-web@v0.0.0-20220223060959-ab545e78f20d/prepare/14_concurrent/pool/main.go (about)

     1  package main
     2  
     3  //https://github.com/smallnest/go-concurrent-quiz
     4  import (
     5  	"bytes"
     6  	"fmt"
     7  	"runtime"
     8  	"sync"
     9  	"time"
    10  )
    11  
    12  var pool = sync.Pool{New: func() interface{} { return new(bytes.Buffer) }}
    13  
    14  /*
    15  A: 不能编译
    16  B: 可以编译，运行时正常，内存稳定
    17  C: 可以编译，运行时内存可能暴涨 	答案
    18  D: 可以编译，运行时内存先暴涨，但是过一会会回收掉
    19  */
    20  func main() {
    21  	go func() {
    22  		for {
    23  			processRequest(1 << 28) // 256MiB
    24  		}
    25  	}()
    26  	for i := 0; i < 1000; i++ {
    27  		go func() {
    28  			for {
    29  				processRequest(1 << 10) // 1KiB
    30  			}
    31  		}()
    32  	}
    33  	var stats runtime.MemStats
    34  	for i := 0; ; i++ {
    35  		runtime.ReadMemStats(&stats)
    36  		fmt.Printf("Cycle %d: %dB\n", i, stats.Alloc)
    37  		time.Sleep(time.Second)
    38  		runtime.GC()
    39  	}
    40  }
    41  func processRequest(size int) {
    42  	b := pool.Get().(*bytes.Buffer)
    43  	time.Sleep(500 * time.Millisecond)
    44  	b.Grow(size)
    45  	pool.Put(b)
    46  	time.Sleep(1 * time.Millisecond)
    47  }