评测报告：.NET的性能仍然远远落后于Java
每个人都看过各种不同的benchmark，有证明.NET比Java快的，也有证明Java比.NET快的。在某些人的手里，benchmark是一面魔镜，透过它能看到想看的东西。所以，当这位名为Cameron的先生要开始在.NET和Java之间做一个benchmark时，他认为自己就是在浪费时间，因为肯定会有人来证明.NET比Java快。
顺便地，Cameron先生提出了10条“不要用于在.NET和Java之间做选择”的理由，其中包括：
Ø 在某一组特定的benchmark中，某一个比另一个快一点；
Ø Microsoft或Sun（或者Oracle、IBM……）的报告说其中一个比另一个好得多；
Ø 你喜欢（或不喜欢）Bill Gates或者Scott McNeally（或者Larry Ellison）；
Ø 你认为Microsoft或者Sun（或者IBM或者Oracle）很邪恶（或者很伟大）；
Ø 你在TheServerSide.com或者GotDotNet.com（或者Microsoft.com）读了一篇“没有偏见”的文章；
实际上，这次benchmark源于Cameron与tRolf两人在TheServerSide.com网站的一次关于Web服务性能的争吵（http://www.theserverside.com/reviews/thread.jsp?thread_id=19226）。在这次的benchmark中，Cameron测试了下列版本：
.NET 1.0sp2:
Microsoft (R) Visual C# .NET Compiler version 7.00.9466
for Microsoft (R) .NET Framework version 1.0.3705
Copyright (C) Microsoft Corporation 2001. All rights reserved.
.NET 1.1:
Microsoft (R) Visual C# .NET Compiler version 7.10.3052.4
for Microsoft (R) .NET Framework version 1.1.4322
Copyright (C) Microsoft Corporation 2001-2002. All rights reserved.
Sun Hotspot Server JVM from JDK 1.3.1_04:
java version "1.3.1_04"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1_04-b02)
Java HotSpot(TM) Server VM (build 1.3.1_04-b02, mixed mode)
Sun Hotspot Server JVM from JDK 1.4.0_02:
java version "1.4.0_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0_02-b02)
Java HotSpot(TM) Server VM (build 1.4.0_02-b02, mixed mode)
Sun Hotspot Server JVM from JDK 1.4.1_02:
java version "1.4.1_02"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.1_02-b06)
Java HotSpot(TM) Client VM (build 1.4.1_02-b06, mixed mode)
在代码方面，Cameron主要选择了大量ArrayList来进行测试。下列是他的测试代码：
C#
// C# Create 100,000 people in an ArrayList and access them
using System;
using System.Collections;
public class ManyPeople
{
public static void Main()
{
for (int i = 0; i < 100; i++)
test(i);
}
public static void test(int iIter)
{
DateTime start = DateTime.Now;
for (int i = 0; i < 20; i++)
new ManyPeople().Average();
DateTime finish = DateTime.Now;
Console.WriteLine("Total time for iteration " + iIter + ": " + (finish - start));
}
private long Average()
{
ArrayList list = new ArrayList(100000);
for (int i = 0; i < 100000; i++)
list.Add(new Person(i, "John " + i));
long silly = 0;
foreach (Person p in list)
silly += p.Id;
return silly / 100000;
}
}
// Person.cs: a very simple guy
public class Person
{
int id;
string name;
public Person(int anId, string aName)
{
this.id = anId;
this.name = aName;
}
public int Id
{
get { return this.id; }
}
}
Java:
// Java Create 100,000 people in an ArrayList and access them
import java.util.*;
public class ManyPeople
{
public static void main(String[] args)
{
for (int i = 0; i < 100; i++)
test(i);
}
public static void test(int iIter)
{
long start = System.currentTimeMillis();
for (int i = 0; i < 20; i++)
new ManyPeople().average();
long finish = System.currentTimeMillis();
System.out.println("Total time for iteration " + iIter + ": " + (finish - start));
}
private long average()
{
ArrayList list = new ArrayList(100000);
for (int i = 0; i < 100000; i++)
list.add(new Person(i, "John " + i));
long silly = 0;
for (int i = 0; i < 100000; i++)
silly += ((Person)list.get(i)).getId();
return silly;
}
}
// Person.java: a very simple guy
class Person
{
private int id;
private String name;
public Person(int anId, String aName)
{
this.id = anId;
this.name = aName;
}
public int getId()
{
return this.id;
}
}
Cameron所用的测试机器是P3 1GHz、1G内存的笔记本，操作系统是Windows 2000 SP2。下列是在.NET上测试的结果（取最好的6次）：
.NET 1.0sp2:
ManyPeople
Total time for iteration 0: 00:00:07.3004976
Total time for iteration 1: 00:00:07.0501376
Total time for iteration 2: 00:00:07.2504256
Total time for iteration 3: 00:00:07.7311168
Total time for iteration 4: 00:00:07.5007856
Total time for iteration 5: 00:00:07.5007856
.NET 1.1:
ManyPeople
Total time for iteration 0: 00:00:08.0916352
Total time for iteration 1: 00:00:08.5222544
Total time for iteration 2: 00:00:08.3520096
Total time for iteration 3: 00:00:08.6324128
Total time for iteration 4: 00:00:08.3419952
Total time for iteration 5: 00:00:08.1617360
可以看到，同样的代码在.NET 1.1上比.NET 1.0 SP2上慢了大约15%。这是一个很奇怪的现象。并且，Cameron观察到，.NET上同样代码的运行速度并不随运行次数的增加而提高，说明.NET CLR只是简单地进行了JIT编译。而在Hotspot Server上，不仅开始时的性能就有优势，而且速度还会不断提高：
Sun Hotspot Server JVM from JDK 1.4.1_02:
java -server -Xms128m -Xmx128m ManyPeople
Total time for iteration 0: 6370
Total time for iteration 1: 5788
Total time for iteration 2: 5868
Total time for iteration 3: 6029
Total time for iteration 4: 5748
Total time for iteration 5: 5738
Total time for iteration 6: 5729
Total time for iteration 7: 5948
Total time for iteration 8: 5688
Total time for iteration 9: 5679
Total time for iteration 10: 5658
Total time for iteration 11: 6028
Total time for iteration 12: 5699
Total time for iteration 13: 5708
Total time for iteration 14: 5678
Total time for iteration 15: 5969
Total time for iteration 16: 5628
Total time for iteration 17: 5538
Total time for iteration 18: 5608
Total time for iteration 19: 5498
Total time for iteration 20: 5768
Total time for iteration 21: 5518
Total time for iteration 22: 5307
Total time for iteration 23: 4247
Total time for iteration 24: 4696
Total time for iteration 25: 4617
Total time for iteration 26: 4777
Total time for iteration 27: 4286
Total time for iteration 28: 4677
Total time for iteration 29: 4626
Total time for iteration 30: 4697
Total time for iteration 31: 4286
Total time for iteration 32: 4697
Total time for iteration 33: 4617
Total time for iteration 34: 4696
Total time for iteration 35: 4307
Total time for iteration 36: 4686
Total time for iteration 37: 4807
Total time for iteration 38: 4517
Total time for iteration 39: 4306
Total time for iteration 40: 4657
Total time for iteration 41: 4807
Total time for iteration 42: 4596
Total time for iteration 43: 4206
Total time for iteration 44: 4777
Total time for iteration 45: 4717
Total time for iteration 46: 4607
Total time for iteration 47: 4196
Total time for iteration 48: 4796
Total time for iteration 49: 4707
Total time for iteration 50: 4777
Total time for iteration 51: 4196
Total time for iteration 52: 4627
Total time for iteration 53: 4687
Total time for iteration 54: 4806
Total time for iteration 55: 4186
Total time for iteration 56: 4627
Total time for iteration 57: 4697
Total time for iteration 58: 4807
Total time for iteration 59: 4166
Total time for iteration 60: 4616
Total time for iteration 61: 4697
Total time for iteration 62: 4717
Total time for iteration 63: 4346
Total time for iteration 64: 4717
Total time for iteration 65: 4617
Total time for iteration 66: 4626
Total time for iteration 67: 4367
Total time for iteration 68: 4706
Total time for iteration 69: 4617
Total time for iteration 70: 4617
Total time for iteration 71: 4366
Total time for iteration 72: 4687
Total time for iteration 73: 4616
Total time for iteration 74: 4196
Total time for iteration 75: 4787
Total time for iteration 76: 4687
Total time for iteration 77: 4807
Total time for iteration 78: 4436
Total time for iteration 79: 4387
Total time for iteration 80: 4676
Total time for iteration 81: 4807
Total time for iteration 82: 4417
Total time for iteration 83: 4296
Total time for iteration 84: 4686
Total time for iteration 85: 4797
Total time for iteration 86: 4266
Total time for iteration 87: 4697
Total time for iteration 88: 4617
Total time for iteration 89: 4717
Total time for iteration 90: 4276
Total time for iteration 91: 4707
Total time for iteration 92: 4616
Total time for iteration 93: 4697
Total time for iteration 94: 4296
Total time for iteration 95: 4677
Total time for iteration 96: 4546
Total time for iteration 97: 4697
Total time for iteration 98: 4296
Total time for iteration 99: 4677
可以看到，随着运行次数的增加，Sun Hotspot Server不断将领先优势拉大，最后几乎比.NET 1.1快了一倍。.NET CLR始终无法将运行时间降低到8秒以下，而Sun Hotspot Server在多次运行之后则可以保持在5秒以下。因此，Cameron认为，对于大运算量的应用程序，Hotspot JVM比Microsoft CLR要快得多。
原文及完整的benchmark数据请看Cameron的blog：
http://www.freeroller.net/page/cpurdy/20030516
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