主题：【倡议】Java SE 5.0和.NET 2.0擂台赛 -- Highway

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家园 【倡议】Java SE 5.0和.NET 2.0擂台赛
现在,Java的一个重要版本终于面世了。不管怎么说，这是继Java 1.2之后的一个阶段性发展。而微软的.NET 2.0 Beta版本已经发布一段时间了。这两种技术在今后一段时间内将是应用程序市场开发的主流。希望大家就这两种技术提出自己的看法。不限形势，不限内容，大家尽可畅所欲言。比如两者性能有什么区别，功能有什么差异，Garbage Collection技术细节上有何异同，安装，发布的难度如何，和以往版本的兼容性如何等等。
总之一句话，希望大家踊跃发言！
- 复【倡议】Java SE 5.0和.NET 2.0擂台赛
  家园 两位的二人转很热闹啊
  有没兴趣我们搞一个soft 的benchmark 网站?
  software 版本的 tomshardware.
  - 复两位的二人转很热闹啊
    家园 这种网站已经不可计数了，何必再搞一个呢？
    你有什么别人没有的特色吗？
    你能commit多少时间？我们搞这样的网站目的何在？
    - 复这种网站已经不可计数了，何必再搞一个呢？
      家园 俺是不行啊
      其实只是想论坛的方式总有它的局限性, 即使老铁
      在努力, 有些东西是没法改变的.
      需要多种方式互补. 比如这样的专业讨论我觉得用wiki的方式就比较好,
      比如你和老兵, 可以共同修改一个文章, 别人也可以修改或者
      加注. 有兴趣就写, 没兴趣就不写.
      - 复俺是不行啊
        家园 php wiki 我考虑在新版后花点时间玩玩。觉得坛子里的好文章应该有个方式
        来整合一下，做个资料库。wiki可能会是个好手段。
        复 php wiki 我考虑在新版后花点时间玩玩。觉得坛子里的好文章应该有个方式
        家园 呀..
        比如期刊, 我感觉用wiki的方式就很好, 主要是
        1. 方便大家参与
        2. 方便维护
        我在database上装了个mediawiki, 有空可以试试看, 感觉一下是
        不是好用.
      - 复俺是不行啊
        家园 如果有人出钱，我一定会有积极性。
        否则，还是看看球赛，混混日子吧！
        复如果有人出钱，我一定会有积极性。
        家园 老兵肯定有积蓄
        而且很有事业心的样子..
- 复【倡议】Java SE 5.0和.NET 2.0擂台赛
  家园
  String, StringBuffer &StringBuilder的玄妙
  String可能是使用最广泛的一种操作了，尤其是在现在Web程序开发中。事实上，Java的String是非常特殊的一种Class，即所有的String Object都是Immutable的。为什么要这样对待String呢？因为Sun想尽可能的榨取一切可能的性能。
  为了提高连续拼接String的性能，Java提供了一个类叫StringBuffer。使用它在某些情况下可以成千倍的提高性能。但是Sun还是不够满意，在Java 5.0中，它又提供了一个类叫做StringBuilder。
  那么StringBuilder和StringBuffer有什么区别呢？StringBuffer是Thread-safe的，而StringBuilder不是。
  那么什么是Thread-safe呢？还记得国内火车内的那种厕所吗？一个人进去，把门一锁，然后开始“方便”。其间不会被外人打扰。完事后开门出来，下一个人才能进去。不会有两个人同时一起“方便”的尴尬局面。这就是Thread-safe.显然Thread-safe有一定的开销，比如关门，上锁，开门等等。在有些情况下，我们不需要这么safe，比如在家里（如果只有你和你老婆），或者你是单身汉，家里根本就没外人。在这种情况下，不用Thread-safe可能会更方便一些，效率会更高。
  StringBuilder就是这样的设计思想。在一切可能的情况下使用StringBuilder，最大限度的提高性能。
  大家看看下面这段小程序，就会有些感性认识了。
  源程序
```
......
        String[] strs = null;
        strs = this.prepareString(5000);
        this.stringBufferTest(strs);
        this.stringBuilderTest(strs);
        this.stringTest(strs);
        
        strs = this.prepareString(20000);
        this.stringBufferTest(strs);
        this.stringBuilderTest(strs);
        //this.stringTest(strs);
        
        strs = this.prepareString(100000);
        this.stringBufferTest(strs);
        this.stringBuilderTest(strs);
        //this.stringTest(strs);    
......
    private String[] prepareString(int number){
        System.out.println("String number: " + number);
        String[] strs = new String[number];
        for(int i=0; i<number; i++)
            strs[i] = "Highway" + i;
        return strs;
    }
    private void stringBuilderTest(String[] input){
        long start = System.currentTimeMillis();
        StringBuilder sb = new StringBuilder();
        for(int i=0; i<input.length; i++)
            sb.append(input[i]);
        long time = System.currentTimeMillis()-start;
        System.out.println("StringBuilder Takes Time: " + time + "ms");
        return;
    }
    private void stringBufferTest(String[] input){
        long start = System.currentTimeMillis();
        StringBuffer sb = new StringBuffer();
        for(int i=0; i<input.length; i++)
            sb.append(input[i]);
        long time = System.currentTimeMillis()-start;
        System.out.println("StringBuffer Takes Time: " + time+ "ms");
        return;
    }
    private void stringTest(String[] input){
        long start = System.currentTimeMillis();
        String sb = "";
        for(int i=0; i<input.length; i++)
            sb = sb + input[i];
        long time = System.currentTimeMillis()-start;
        System.out.println("String Append Takes Time: " + time+ "ms");
        return;
    }    
```
  反编译得到的程序，这是Java实际工作的Code.
```
    private String[] prepareString(int number)
    {
        System.out.println((new StringBuilder()).append("String number: ").append(number).toString());
        String strs[] = new String[number];
        for(int i = 0; i < number; i++)
            strs[i] = (new StringBuilder()).append("Highway").append(i).toString();

        return strs;
    }

    private void stringBuilderTest(String input[])
    {
        long start = System.currentTimeMillis();
        StringBuilder sb = new StringBuilder();
        for(int i = 0; i < input.length; i++)
            sb.append(input[i]);

        long time = System.currentTimeMillis() - start;
        System.out.println((new StringBuilder()).append("StringBuilder Takes Time: ").append(time).append("ms").toString());
    }

    private void stringBufferTest(String input[])
    {
        long start = System.currentTimeMillis();
        StringBuffer sb = new StringBuffer();
        for(int i = 0; i < input.length; i++)
            sb.append(input[i]);

        long time = System.currentTimeMillis() - start;
        System.out.println((new StringBuilder()).append("StringBuffer Takes Time: ").append(time).append("ms").toString());
    }

    private void stringTest(String input[])
    {
        long start = System.currentTimeMillis();
        String sb = "";
        for(int i = 0; i < input.length; i++)
            sb = (new StringBuilder()).append(sb).append(input[i]).toString();

        long time = System.currentTimeMillis() - start;
        System.out.println((new StringBuilder()).append("String Append Takes Time: ").append(time).append("ms").toString());
    }
```
  由上可见，Java在内部尽可能的在使用StringBuilder
  [SIZE=3]测试结果：[/SIZE]
```
String number: 5000
StringBuffer Takes Time: 15ms
StringBuilder Takes Time: 0ms
String Append Takes Time: 7281ms
String number: 20000
StringBuffer Takes Time: 31ms
StringBuilder Takes Time: 16ms
String number: 100000
StringBuffer Takes Time: 188ms
StringBuilder Takes Time: 156ms
```
  由此可见，StringBuilder 确实是有效果的。最慢的是String直接拼接，效果满上千倍，这是大家应该避免的情况。
  那么.NET如何呢？.NET只有一个StringBuilder，没有StringBuffer。这个StringBuilder的Public static变量是Thread-safe的，而instance members却不是。哈哈，有意思吧！！！
  将上面Java的程序用.NET写一遍，其运行结果比Java快很多，尤其是赤裸裸的SString拼接（20倍）。这是一个很有趣的问题。希望大家能帮我解释一下为什么！！！
```
String number: 5000
StringBuilder Takes Time: 0ms
String Append Takes Time: 422ms
String number: 20000
StringBuilder Takes Time: 15ms
String number: 100000
StringBuilder Takes Time: 32ms
```
  C#源程序为：
```
        private String[] prepareString(int number)
        {
            System.Console.WriteLine("String number: " + number);
            String[] strs = new String[number];
            for(int i=0; i<number; i++)
                strs[i] = "Highway" + i;
            return strs;
        }
        private void stringBuilderTest(String[] input)
        {
            long start = System.Environment.TickCount;
            StringBuilder sb = new StringBuilder();
            for(int i=0; i<input.Length; i++)
                sb.Append(input[i]);
            long time = System.Environment.TickCount - start;
            System.Console.WriteLine("StringBuilder Takes Time: " + time + "ms");
            return;
        }

        private void stringTest(String[] input)
        {
            long start = System.Environment.TickCount;
            String sb = "";
            for(int i=0; i<input.Length; i++)
                sb = sb + input[i];
            long time = System.Environment.TickCount - start;
            System.Console.WriteLine("String Append Takes Time: " + time + "ms");
            return;
        }
```
  反编译后为：
```
private void stringBuilderTest(string[] input)
{
      long num1 = Environment.TickCount;
      StringBuilder builder1 = new StringBuilder();
      for (int num2 = 0; num2 < input.Length; num2++)
      {
            builder1.Append(input[num2]);
      }
      long num3 = Environment.TickCount - num1;
      Console.WriteLine("StringBuilder Takes Time: " + num3 + "ms");
}
 
private void stringTest(string[] input)
{
      long num1 = Environment.TickCount;
      string text1 = "";
      for (int num2 = 0; num2 < input.Length; num2++)
      {
            text1 = text1 + input[num2];
      }
      long num3 = Environment.TickCount - num1;
      Console.WriteLine("String Append Takes Time: " + num3 + "ms");
}
```
  - 复 String, StringBuffer &StringBuilder的玄妙
    家园 我对.Net2.0 Beta1下StringBuilder的测试结果
    首先，我对老轧的程序进行了一些简单的修改，主要如下：
    一。取消了对String的测试部分，而只测试StringBuilder，因为String的性能明显落后，测试的意义不大。
    二。测试范围从1000到100，000，步长为1000，这样可以看出一些比较细的东西。
    下面是我的测试代码：
    #region Using directives
    using System;
    using System.Collections.Generic;
    using System.Text;
    #endregion
    namespace StringTest
    {
    class Program
    {
    private String[] prepareString(int number)
    {
    System.Console.WriteLine("String number: " + number);
    String[] strs = new String[number];
    for (int i = 0; i < number; i++)
    strs[i] = "Highway" + i;
    return strs;
    }
    private void stringBuilderTest(String[] input)
    {
    long start = System.Environment.TickCount;
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < input.Length; i++)
    sb.Append(input[i]);
    long time = System.Environment.TickCount - start;
    System.Console.WriteLine("StringBuilder Takes Time: " + time + "ms");
    return;
    }
    public void test()
    {
    String[] strs = null;
    for (int i = 1; i <= 100; i++)
    {
    strs = this.prepareString(i * 1000);
    this.stringBuilderTest(strs);
    }
    }
    static void Main(string[] args)
    {
    Program p = new Program();
    p.test();
    }
    }
    }
    在将Build结果从Debug设定为Release并且设定目标CPU为x86以后，我得到以下的测试结果：
    String number: 1000
    StringBuilder Takes Time: 0ms
    String number: 2000
    StringBuilder Takes Time: 0ms
    String number: 3000
    StringBuilder Takes Time: 0ms
    String number: 4000
    StringBuilder Takes Time: 0ms
    String number: 5000
    StringBuilder Takes Time: 0ms
    String number: 6000
    StringBuilder Takes Time: 0ms
    String number: 7000
    StringBuilder Takes Time: 0ms
    String number: 8000
    StringBuilder Takes Time: 0ms
    String number: 9000
    StringBuilder Takes Time: 16ms
    String number: 10000
    StringBuilder Takes Time: 15ms
    String number: 11000
    StringBuilder Takes Time: 0ms
    String number: 12000
    StringBuilder Takes Time: 0ms
    String number: 13000
    StringBuilder Takes Time: 15ms
    String number: 14000
    StringBuilder Takes Time: 16ms
    String number: 15000
    StringBuilder Takes Time: 0ms
    String number: 16000
    StringBuilder Takes Time: 16ms
    String number: 17000
    StringBuilder Takes Time: 15ms
    String number: 18000
    StringBuilder Takes Time: 16ms
    String number: 19000
    StringBuilder Takes Time: 0ms
    String number: 20000
    StringBuilder Takes Time: 16ms
    String number: 21000
    StringBuilder Takes Time: 16ms
    String number: 22000
    StringBuilder Takes Time: 16ms
    String number: 23000
    StringBuilder Takes Time: 15ms
    String number: 24000
    StringBuilder Takes Time: 0ms
    String number: 25000
    StringBuilder Takes Time: 0ms
    String number: 26000
    StringBuilder Takes Time: 0ms
    String number: 27000
    StringBuilder Takes Time: 16ms
    String number: 28000
    StringBuilder Takes Time: 0ms
    String number: 29000
    StringBuilder Takes Time: 0ms
    String number: 30000
    StringBuilder Takes Time: 0ms
    String number: 31000
    StringBuilder Takes Time: 0ms
    String number: 32000
    StringBuilder Takes Time: 0ms
    String number: 33000
    StringBuilder Takes Time: 31ms
    String number: 34000
    StringBuilder Takes Time: 31ms
    String number: 35000
    StringBuilder Takes Time: 46ms
    String number: 36000
    StringBuilder Takes Time: 0ms
    String number: 37000
    StringBuilder Takes Time: 0ms
    String number: 38000
    StringBuilder Takes Time: 15ms
    String number: 39000
    StringBuilder Takes Time: 16ms
    String number: 40000
    StringBuilder Takes Time: 16ms
    String number: 41000
    StringBuilder Takes Time: 31ms
    String number: 42000
    StringBuilder Takes Time: 0ms
    String number: 43000
    StringBuilder Takes Time: 31ms
    String number: 44000
    StringBuilder Takes Time: 31ms
    String number: 45000
    StringBuilder Takes Time: 16ms
    String number: 46000
    StringBuilder Takes Time: 63ms
    String number: 47000
    StringBuilder Takes Time: 0ms
    String number: 48000
    StringBuilder Takes Time: 63ms
    String number: 49000
    StringBuilder Takes Time: 47ms
    String number: 50000
    StringBuilder Takes Time: 16ms
    String number: 51000
    StringBuilder Takes Time: 47ms
    String number: 52000
    StringBuilder Takes Time: 32ms
    String number: 53000
    StringBuilder Takes Time: 16ms
    String number: 54000
    StringBuilder Takes Time: 47ms
    String number: 55000
    StringBuilder Takes Time: 31ms
    String number: 56000
    StringBuilder Takes Time: 16ms
    String number: 57000
    StringBuilder Takes Time: 62ms
    String number: 58000
    StringBuilder Takes Time: 47ms
    String number: 59000
    StringBuilder Takes Time: 16ms
    String number: 60000
    StringBuilder Takes Time: 78ms
    String number: 61000
    StringBuilder Takes Time: 47ms
    String number: 62000
    StringBuilder Takes Time: 15ms
    String number: 63000
    StringBuilder Takes Time: 63ms
    String number: 64000
    StringBuilder Takes Time: 47ms
    String number: 65000
    StringBuilder Takes Time: 15ms
    String number: 66000
    StringBuilder Takes Time: 62ms
    String number: 67000
    StringBuilder Takes Time: 46ms
    String number: 68000
    StringBuilder Takes Time: 0ms
    String number: 69000
    StringBuilder Takes Time: 62ms
    String number: 70000
    StringBuilder Takes Time: 47ms
    String number: 71000
    StringBuilder Takes Time: 16ms
    String number: 72000
    StringBuilder Takes Time: 79ms
    String number: 73000
    StringBuilder Takes Time: 62ms
    String number: 74000
    StringBuilder Takes Time: 31ms
    String number: 75000
    StringBuilder Takes Time: 125ms
    String number: 76000
    StringBuilder Takes Time: 16ms
    String number: 77000
    StringBuilder Takes Time: 31ms
    String number: 78000
    StringBuilder Takes Time: 94ms
    String number: 79000
    StringBuilder Takes Time: 15ms
    String number: 80000
    StringBuilder Takes Time: 15ms
    String number: 81000
    StringBuilder Takes Time: 16ms
    String number: 82000
    StringBuilder Takes Time: 16ms
    String number: 83000
    StringBuilder Takes Time: 15ms
    String number: 84000
    StringBuilder Takes Time: 16ms
    String number: 85000
    StringBuilder Takes Time: 15ms
    String number: 86000
    StringBuilder Takes Time: 16ms
    String number: 87000
    StringBuilder Takes Time: 15ms
    String number: 88000
    StringBuilder Takes Time: 31ms
    String number: 89000
    StringBuilder Takes Time: 94ms
    String number: 90000
    StringBuilder Takes Time: 15ms
    String number: 91000
    StringBuilder Takes Time: 31ms
    String number: 92000
    StringBuilder Takes Time: 32ms
    String number: 93000
    StringBuilder Takes Time: 15ms
    String number: 94000
    StringBuilder Takes Time: 31ms
    String number: 95000
    StringBuilder Takes Time: 31ms
    String number: 96000
    StringBuilder Takes Time: 31ms
    String number: 97000
    StringBuilder Takes Time: 31ms
    String number: 98000
    StringBuilder Takes Time: 16ms
    String number: 99000
    StringBuilder Takes Time: 15ms
    String number: 100000
    StringBuilder Takes Time: 32ms
    和我对Java的对应测试相比，测试结果基本等同于Java StringBuilder所对应的结果，不管它是在Server模式下还是Client模式。
    注：以上测试结果是在一台运行Windows XP Pro+SP2, 512M内存，Visual Studio 2005 Beta1+.Net 2.0 Beta1的机器上得出的。
  - 复 String, StringBuffer &StringBuilder的玄妙
    家园 我对Java StringBuffer/StringBuilder的测试结果
    首先，我对老轧的程序进行了一些简单的修改，主要如下：
    一。取消了对String的测试部分，而只测试StringBuffer和StringBuilder，因为String的性能明显落后，测试的意义不大。
    二。测试范围从1000到100，000，步长为1000，这样可以看出一些比较细的东西。
    三。每组测试后，我调用了System.gc()来建议JVM立刻进行内存回收，其目的是最小化前次试验对后续试验由于不定期的内存回收所造成的性能震荡。
    其次，我的实验分为使用-Client和-Server两种，目的是比较不同参数下的同级别测试的性能差异，另外，所使用的参数还包括了-Xms256M -Xmx256M。
    下面是我的测试代码：
    package test2005_2;
    class StringTest {
    private String[] prepareString(int number) {
    System.out.println("String number: " + number);
    String[] strs = new String[number];
    for (int i = 0; i < number; i++) {
    strs[i] = "Highway" + i;
    }
    return strs;
    }
    private void stringBuilderTest(String[] input) {
    long start = System.currentTimeMillis();
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < input.length; i++) {
    sb.append(input[i]);
    }
    long time = System.currentTimeMillis() - start;
    System.out.println("StringBuilder Takes Time: " + time + "ms");
    }
    private void stringBufferTest(String[] input) {
    long start = System.currentTimeMillis();
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < input.length; i++) {
    sb.append(input[i]);
    }
    long time = System.currentTimeMillis() - start;
    System.out.println("StringBuffer Takes Time: " + time + "ms");
    }
    public void test() {
    String[] strs = null;
    for (int i = 1; i <= 100; i++) {
    strs = this.prepareString(i * 1000);
    this.stringBufferTest(strs);
    this.stringBuilderTest(strs);
    System.gc();
    }
    }
    public static void main(String[] args) {
    StringTest stringtest = new StringTest();
    stringtest.test();
    }
    }
    下面是使用了-Server -Xms256M -Xmx256M参数情况下的测试结果：
    String number: 1000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 2000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 3000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 4000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 0ms
    String number: 5000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 6000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 7000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 8000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 9000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 10000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 11000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 12000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 13000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 14000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 15000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 16000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 17000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 0ms
    String number: 18000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 19000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 20000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 21000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 22000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 23000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 24000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 25000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 26000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 27000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 28000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 29000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 31ms
    String number: 30000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 31000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 0ms
    String number: 32000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 31ms
    String number: 33000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 34000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 35000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 36000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 37000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 38000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 39000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 40000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 41000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 42000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 43000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 44000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 45000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 46000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 47000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 48000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 32ms
    String number: 49000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 15ms
    String number: 50000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 15ms
    String number: 51000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 31ms
    String number: 52000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 15ms
    String number: 53000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 54000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 55000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 16ms
    String number: 56000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 16ms
    String number: 57000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 58000
    StringBuffer Takes Time: 32ms
    StringBuilder Takes Time: 15ms
    String number: 59000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 60000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 61000
    StringBuffer Takes Time: 32ms
    StringBuilder Takes Time: 15ms
    String number: 62000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 63000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 31ms
    String number: 64000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 65000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 66000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 67000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 68000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 69000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 70000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 47ms
    String number: 71000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 47ms
    String number: 72000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 32ms
    String number: 73000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 46ms
    String number: 74000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 75000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 32ms
    String number: 76000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 31ms
    String number: 77000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 32ms
    String number: 78000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 31ms
    String number: 79000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 80000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 16ms
    String number: 81000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 31ms
    String number: 82000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 83000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 84000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 85000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 46ms
    String number: 86000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 63ms
    String number: 87000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 0ms
    String number: 88000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 47ms
    String number: 89000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 90000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 91000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 92000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 15ms
    String number: 93000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 15ms
    String number: 94000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 15ms
    String number: 95000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 0ms
    String number: 96000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 47ms
    String number: 97000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 0ms
    String number: 98000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 99000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 16ms
    String number: 100000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 94ms
    下面是使用了 -Client -Xms256M -Xmx256M参数情况下的测试结果：
    String number: 1000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 2000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 3000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 4000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 5000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 6000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 7000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 8000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 15ms
    String number: 9000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 10000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 11000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 12000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 13000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 14000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 15000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 16000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 17000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 18000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 0ms
    String number: 19000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 20000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 21000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 22000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 23000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 0ms
    String number: 24000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 25000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 26000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 27000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 28000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 15ms
    String number: 29000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 30000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 0ms
    String number: 31000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 32000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 0ms
    String number: 33000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 0ms
    String number: 34000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 35000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 0ms
    String number: 36000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 37000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 0ms
    String number: 38000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 39000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 40000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 41000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 42000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 43000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 16ms
    String number: 44000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 45000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 46000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 31ms
    String number: 47000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 15ms
    String number: 48000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 49000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 0ms
    String number: 50000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 51000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 31ms
    String number: 52000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 16ms
    String number: 53000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 15ms
    String number: 54000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 16ms
    String number: 55000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 62ms
    String number: 56000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 63ms
    String number: 57000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 63ms
    String number: 58000
    StringBuffer Takes Time: 32ms
    StringBuilder Takes Time: 62ms
    String number: 59000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 47ms
    String number: 60000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 47ms
    String number: 61000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 63ms
    String number: 62000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 78ms
    String number: 63000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 78ms
    String number: 64000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 94ms
    String number: 65000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 62ms
    String number: 66000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 78ms
    String number: 67000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 78ms
    String number: 68000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 78ms
    String number: 69000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 78ms
    String number: 70000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 78ms
    String number: 71000
    StringBuffer Takes Time: 0ms
    StringBuilder Takes Time: 78ms
    String number: 72000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 78ms
    String number: 73000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 62ms
    String number: 74000
    StringBuffer Takes Time: 31ms
    StringBuilder Takes Time: 78ms
    String number: 75000
    StringBuffer Takes Time: 15ms
    StringBuilder Takes Time: 78ms
    String number: 76000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 78ms
    String number: 77000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 62ms
    String number: 78000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 62ms
    String number: 79000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 63ms
    String number: 80000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 47ms
    String number: 81000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 63ms
    String number: 82000
    StringBuffer Takes Time: 16ms
    StringBuilder Takes Time: 78ms
    String number: 83000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 78ms
    String number: 84000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 63ms
    String number: 85000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 62ms
    String number: 86000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 62ms
    String number: 87000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 78ms
    String number: 88000
    StringBuffer Takes Time: 47ms
    StringBuilder Takes Time: 62ms
    String number: 89000
    StringBuffer Takes Time: 46ms
    StringBuilder Takes Time: 79ms
    String number: 90000
    StringBuffer Takes Time: 94ms
    StringBuilder Takes Time: 15ms
    String number: 91000
    StringBuffer Takes Time: 94ms
    StringBuilder Takes Time: 15ms
    String number: 92000
    StringBuffer Takes Time: 94ms
    StringBuilder Takes Time: 15ms
    String number: 93000
    StringBuffer Takes Time: 78ms
    StringBuilder Takes Time: 0ms
    String number: 94000
    StringBuffer Takes Time: 93ms
    StringBuilder Takes Time: 16ms
    String number: 95000
    StringBuffer Takes Time: 110ms
    StringBuilder Takes Time: 0ms
    String number: 96000
    StringBuffer Takes Time: 94ms
    StringBuilder Takes Time: 0ms
    String number: 97000
    StringBuffer Takes Time: 78ms
    StringBuilder Takes Time: 15ms
    String number: 98000
    StringBuffer Takes Time: 78ms
    StringBuilder Takes Time: 16ms
    String number: 99000
    StringBuffer Takes Time: 94ms
    StringBuilder Takes Time: 15ms
    String number: 100000
    StringBuffer Takes Time: 94ms
    StringBuilder Takes Time: 31ms
    测试结果概述：
    一。对于使用了-Server参数的测试，我们可以看出以下结果：
    1。在35000以前，结果是不确定的，也就是说，交替出现了某方为0的结果。
    2。从35000到69000，基本是交替领先，领先次数基本是平局。
    3。从70000到100000，StringBuffer领先于StringBuilder的比例是22:8。
    结论，在这样的测试环境下，StringBuffer的总体表现要比StringBuilder强！
    二。对于使用了-Client参数的测试，我们可以看出以下结果：
    1。在50000以前，结果是不确定的，也就是说，交替出现了某方为0的结果。
    2。从50000到89000，StringBuffer领先于StringBuilder的比例是1:36
    3。从90000到100000，StringBuilder领先于StringBuffer的比例是11:0。
    结论：本组测试的101组数据中，前五十组可以认为比较失真，后面的五十组StringBuilder领先于StringBuffer的比例是12:36，而且是只有最后的十一组才体现出StringBuilder的优势，因此我们可以得出结论：只有在非常大的字符串数组情况下，StringBuilder的表现才领先于StringBuffer，否则并不占优势。
    注：以上测试是在一台运行Windows XP Pro+SP2, 512M内存，Java 1.5，JBuilder 2005 Enterprise的机器上得出的。
    - 复我对Java StringBuffer/StringBuilder的测试结果
      家园 其实这种测试波动很大。因为我们没有办法控制GC.
      System.gc()对JVM来说是一个Hint，而不是强制性指令。所以到底什么JVM开始回收内存，是一个不确定的事情。一旦Background thread开始回收内存，前台的程序就会受到极大的影响。这是我们测试的一个难点。
      Calling the gc method suggests that the Java Virtual Machine expend effort toward recycling unused objects in order to make the memory they currently occupy available for quick reuse. When control returns from the method call, the Java Virtual Machine has made a best effort to reclaim space from all discarded objects.
      理论上讲，Thread-safe的操作是有代价的。如果情况允许，我们尽可能避开这个开销！
      - 复其实这种测试波动很大。因为我们没有办法控制GC.
        家园 理论上的确如此
        但是我的测试结果并不支持这种看法，而且测试结果的优劣分布还是比较明显的，很多组数据的差距还是比较大的，而不是在临界的+-1。
        单独的数据疵点可以认为是JVM作GC所导致的结果，但是这样的数据疵点不应该很多，以至于无法改变最后结果。
        另外，我给的内存是256M，对于这样的测试应该是足够的了。
        复理论上的确如此
        家园 看看我的测试结果！
        StringBuiler几乎是一路领先（低端有些交替）！
        java -server -Xmx256M StringTest >perf2.txt
        String number: 1000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 0ms
        String number: 2000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 16ms
        String number: 3000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 15ms
        String number: 4000
        StringBuffer Takes Time: 16ms
        StringBuilder Takes Time: 0ms
        String number: 5000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 15ms
        String number: 6000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 0ms
        String number: 7000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 0ms
        String number: 8000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 0ms
        String number: 9000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 16ms
        String number: 10000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 15ms
        String number: 11000
        StringBuffer Takes Time: 15ms
        StringBuilder Takes Time: 0ms
        String number: 12000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 0ms
        String number: 13000
        StringBuffer Takes Time: 0ms
        StringBuilder Takes Time: 0ms
        String number: 14000
        StringBuffer Takes Time: 16ms
        StringBuilder Takes Time: 15ms
        String number: 15000
        StringBuffer Takes Time: 16ms
        StringBuilder Takes Time: 16ms
        String number: 16000
        StringBuffer Takes Time: 16ms
        StringBuilder Takes Time: 16ms
        String number: 17000
        StringBuffer Takes Time: 16ms
        StringBuilder Takes Time: 15ms
        String number: 18000
        StringBuffer Takes Time: 16ms
        StringBuilder Takes Time: 15ms
        String number: 19000
        StringBuffer Takes Time: 31ms
        StringBuilder Takes Time: 15ms
        String number: 20000
        StringBuffer Takes Time: 31ms
        StringBuilder Takes Time: 16ms
        String number: 21000
        StringBuffer Takes Time: 31ms
        StringBuilder Takes Time: 16ms
        String number: 22000
        StringBuffer Takes Time: 31ms
        StringBuilder Takes Time: 16ms
        String number: 23000
        StringBuffer Takes Time: 31ms
        StringBuilder Takes Time: 16ms
        String number: 24000
        StringBuffer Takes Time: 32ms
        StringBuilder Takes Time: 15ms
        String number: 25000
        StringBuffer Takes Time: 32ms
        StringBuilder Takes Time: 15ms
        String number: 26000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 27000
        StringBuffer Takes Time: 32ms
        StringBuilder Takes Time: 46ms
        String number: 28000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 29000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 32ms
        String number: 30000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 31000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 32000
        StringBuffer Takes Time: 46ms
        StringBuilder Takes Time: 32ms
        String number: 33000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 34000
        StringBuffer Takes Time: 46ms
        StringBuilder Takes Time: 47ms
        String number: 35000
        StringBuffer Takes Time: 46ms
        StringBuilder Takes Time: 32ms
        String number: 36000
        StringBuffer Takes Time: 46ms
        StringBuilder Takes Time: 47ms
        String number: 37000
        StringBuffer Takes Time: 46ms
        StringBuilder Takes Time: 47ms
        String number: 38000
        StringBuffer Takes Time: 46ms
        StringBuilder Takes Time: 47ms
        String number: 39000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 47ms
        String number: 40000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 47ms
        String number: 41000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 16ms
        String number: 42000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 43000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 16ms
        String number: 44000
        StringBuffer Takes Time: 31ms
        StringBuilder Takes Time: 31ms
        String number: 45000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 46000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 47000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 16ms
        String number: 48000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 32ms
        String number: 49000
        StringBuffer Takes Time: 46ms
        StringBuilder Takes Time: 32ms
        String number: 50000
        StringBuffer Takes Time: 47ms
        StringBuilder Takes Time: 31ms
        String number: 51000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 63ms
        String number: 52000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 63ms
        String number: 53000
        StringBuffer Takes Time: 63ms
        StringBuilder Takes Time: 47ms
        String number: 54000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 47ms
        String number: 55000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 63ms
        String number: 56000
        StringBuffer Takes Time: 63ms
        StringBuilder Takes Time: 62ms
        String number: 57000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 47ms
        String number: 58000
        StringBuffer Takes Time: 79ms
        StringBuilder Takes Time: 62ms
        String number: 59000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 63ms
        String number: 60000
        StringBuffer Takes Time: 63ms
        StringBuilder Takes Time: 62ms
        String number: 61000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 62ms
        String number: 62000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 63ms
        String number: 63000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 63ms
        String number: 64000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 63ms
        String number: 65000
        StringBuffer Takes Time: 79ms
        StringBuilder Takes Time: 62ms
        String number: 66000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 62ms
        String number: 67000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 62ms
        String number: 68000
        StringBuffer Takes Time: 79ms
        StringBuilder Takes Time: 62ms
        String number: 69000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 78ms
        String number: 70000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 63ms
        String number: 71000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 63ms
        String number: 72000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 62ms
        String number: 73000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 62ms
        String number: 74000
        StringBuffer Takes Time: 78ms
        StringBuilder Takes Time: 79ms
        String number: 75000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 62ms
        String number: 76000
        StringBuffer Takes Time: 79ms
        StringBuilder Takes Time: 78ms
        String number: 77000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 62ms
        String number: 78000
        StringBuffer Takes Time: 93ms
        StringBuilder Takes Time: 63ms
        String number: 79000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 62ms
        String number: 80000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 63ms
        String number: 81000
        StringBuffer Takes Time: 125ms
        StringBuilder Takes Time: 47ms
        String number: 82000
        StringBuffer Takes Time: 93ms
        StringBuilder Takes Time: 47ms
        String number: 83000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 47ms
        String number: 84000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 47ms
        String number: 85000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 47ms
        String number: 86000
        StringBuffer Takes Time: 93ms
        StringBuilder Takes Time: 47ms
        String number: 87000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 47ms
        String number: 88000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 47ms
        String number: 89000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 47ms
        String number: 90000
        StringBuffer Takes Time: 62ms
        StringBuilder Takes Time: 63ms
        String number: 91000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 46ms
        String number: 92000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 47ms
        String number: 93000
        StringBuffer Takes Time: 93ms
        StringBuilder Takes Time: 47ms
        String number: 94000
        StringBuffer Takes Time: 94ms
        StringBuilder Takes Time: 47ms
        String number: 95000
        StringBuffer Takes Time: 110ms
        StringBuilder Takes Time: 47ms
        String number: 96000
        StringBuffer Takes Time: 109ms
        StringBuilder Takes Time: 47ms
        String number: 97000
        StringBuffer Takes Time: 93ms
        StringBuilder Takes Time: 63ms
        String number: 98000
        StringBuffer Takes Time: 109ms
        StringBuilder Takes Time: 47ms
        String number: 99000
        StringBuffer Takes Time: 109ms
        StringBuilder Takes Time: 47ms
        String number: 100000
        StringBuffer Takes Time: 141ms
        StringBuilder Takes Time: 93ms
        复看看我的测试结果！
        家园 你试着再加个-Xms256M，看看结果如何？
        那就是我的测试结果了。
        问题就出在你只限定了最大可用内存而没有限定最小可用内存上面了，缺省的设置是64M，这经常是不够的。在这样的情况下，应用程序迫使JVM多次调用GC和增加可用内存，这样会影响比较结果的。
        我的测试方案是首先给足内存（至少是尽可能多的内存，以求减少调用GC和内存膨胀的次数），这样才可以比较真实地进行比较。
        Unless you have problems with pauses, try granting as much memory as possible to the virtual machine. The default size (64MB) is often too small.
        Setting -Xms and -Xmx to the same value increases predictability by removing the most important sizing decision from the virtual machine. On the other hand, the virtual machine can't compensate if you make a poor choice.
        Be sure to increase the memory as you increase the number of processors, since allocation can be parallelized

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