System.Threading

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System.Threading命名空间是.Net多线程编程的基础。对于多线程编程在实际工作中一直用的不多，所以了解也就不多。尽管如此，随着多核，多个cpu的出现，大计算量的需要，多线程将越来越受关注。所以打算写个系列博客，以便更多的了解学习多线程的知识。听说.Net4.0中有一个更方便多线程的类库，可惜还没真的见识过，先熟悉System.Threading就当“温故而知新”了

第一篇：从Thread的线程单元状态ApartmentState说起

ApartmentState是一个枚举变量，用来设置线程的单元状态（单元状态的ApartmentState的中文msdn翻译，这个翻译很水，我不能从这四个汉字中确切的了解英文ApartmentState要表达的意思）。ApartmentState有三个枚举值，分别为STA：表示Thread将被创建并进入一个单线程单元，我猜想STA应该是Single Thread Apartment的首字母简拼；MTA：表示Thread将被创建并进入一个多线程单元，还有一个是Unknown，表示没有设置线程的单元状态。我在以前使用Thread的时候，从来没有设置过线程的单元状态，今天要做个试验把这三种状态搞清楚。

使用新new 一个Thread实例之后可以使用SetAppartmentState方法设置线程的单元状态，每个线程只可以设置一次，若再次设置会抛异常，若不知道是否设置了单元状态可以使用Thread类提供的TrySetApartmentState方法来设置；不设置时其线程单元在控制台应用程序中默认是MTA。

试验思路：
1. 使用new 3个Thread的实例，什么都不执行，看两种不同的AppartmentState的Thread的执行顺序如何
2. 同样new 3个Thread实例，执行一段计算代码，看两种不同的AppartmentState执行完全部计算耗时情况

具体的实验代码如下：

C#代码

using System;
using System.Collections.Generic;
using System.Text;
using System.Threading;
using System.Diagnostics;
using System.Collections;
namespace MutiThread
{
class Program
{
static Stopwatch swAll;
static Random r = new Random();
static Hashtable hashTable;
static void Main(string[] args)
{
Start3Thread(ApartmentState.STA);
Console.ReadLine();
}
static void Start3Thread(ApartmentState appartmentState)
{
int threadCn = 3;
hashTable = new Hashtable();
swAll = new Stopwatch();
swAll.Start();
do
{
StartThread(appartmentState);
threadCn--;
} while (threadCn > 0);
}
static void StartThread(ApartmentState appartmentState)
{
Thread t1 = new Thread(new ThreadStart(CalcSomething));
//Thread t1 = new Thread(new ThreadStart(DoNothing));
hashTable.Add(t1.ManagedThreadId, false);
t1.SetApartmentState(appartmentState);
t1.Start();
}
static void CalcSomething()
{
Stopwatch sw = new Stopwatch();
sw.Start();
int[] arr = new int[1000];
for (int i = 0; i < arr.Length; i++)
{
arr[i] = r.Next(1000);
}
//Console.WriteLine("线程" + Thread.CurrentThread.ManagedThreadId
// + "的单元状态是:" + Thread.CurrentThread.GetApartmentState()
// + "；线程状态：" + Thread.CurrentThread.ThreadState
// + "；耗时：" + sw.ElapsedTicks);
hashTable[Thread.CurrentThread.ManagedThreadId] = true;
if (hashTable.Count == 3)
{
bool allFinish = true;
foreach (object key in hashTable.Keys)
{
allFinish = allFinish && (bool)hashTable[key];
}
if (allFinish)
{
swAll.Stop();
Console.WriteLine(Thread.CurrentThread.GetApartmentState().ToString() + "总耗时：" + swAll.ElapsedTicks);
if (Thread.CurrentThread.GetApartmentState() == ApartmentState.STA)
{
hashTable.Clear();
swAll.Reset();
swAll.Start();
Start3Thread(ApartmentState.MTA);
}
}
}
}
static void DoNothing()
{
int times = 3;
do
{
Console.WriteLine("线程" + Thread.CurrentThread.ManagedThreadId
+ "的单元状态是:" + Thread.CurrentThread.GetApartmentState()
+ "；线程状态：" + Thread.CurrentThread.ThreadState);
times--;
} while (times > 0);
}
}
}

using System; using System.Collections.Generic; using System.Text; using System.Threading; using System.Diagnostics; using System.Collections; namespace MutiThread { class Program { static Stopwatch swAll; static Random r = new Random(); static Hashtable hashTable; static void Main(string[] args) { Start3Thread(ApartmentState.STA); Console.ReadLine(); } static void Start3Thread(ApartmentState appartmentState) { int threadCn = 3; hashTable = new Hashtable(); swAll = new Stopwatch(); swAll.Start(); do { StartThread(appartmentState); threadCn--; } while (threadCn > 0); } static void StartThread(ApartmentState appartmentState) { Thread t1 = new Thread(new ThreadStart(CalcSomething)); //Thread t1 = new Thread(new ThreadStart(DoNothing)); hashTable.Add(t1.ManagedThreadId, false); t1.SetApartmentState(appartmentState); t1.Start(); } static void CalcSomething() { Stopwatch sw = new Stopwatch(); sw.Start(); int[] arr = new int[1000]; for (int i = 0; i < arr.Length; i++) { arr[i] = r.Next(1000); } //Console.WriteLine("线程" + Thread.CurrentThread.ManagedThreadId // + "的单元状态是:" + Thread.CurrentThread.GetApartmentState() // + "；线程状态：" + Thread.CurrentThread.ThreadState // + "；耗时：" + sw.ElapsedTicks); hashTable[Thread.CurrentThread.ManagedThreadId] = true; if (hashTable.Count == 3) { bool allFinish = true; foreach (object key in hashTable.Keys) { allFinish = allFinish && (bool)hashTable[key]; } if (allFinish) { swAll.Stop(); Console.WriteLine(Thread.CurrentThread.GetApartmentState().ToString() + "总耗时：" + swAll.ElapsedTicks); if (Thread.CurrentThread.GetApartmentState() == ApartmentState.STA) { hashTable.Clear(); swAll.Reset(); swAll.Start(); Start3Thread(ApartmentState.MTA); } } } } static void DoNothing() { int times = 3; do { Console.WriteLine("线程" + Thread.CurrentThread.ManagedThreadId + "的单元状态是:" + Thread.CurrentThread.GetApartmentState() + "；线程状态：" + Thread.CurrentThread.ThreadState); times--; } while (times > 0); } } }

实验的结果是：
1. AppartmentState为STA或者MTA时的执行顺序都是不定的，每一次执行都可能不同，也就是说顺序上无法说明两种的区别。
2. 两种不同的ApartmentState的执行效率上是有区别的，单线程单元状态模式所耗时间明显多于多线程单元模式状态
3. 在不设置线程的AppartmentState时，默认值是MTA，也就是多线程模式的