14.并发与异步 - 1.线程处理Thread -《果壳中的c#》

14.2.1 创建一个线程

Thread

Thread

ThreadStart

//System.Threading.ThreadStart 委托，它表示此线程开始执行时要调用的方法
public Thread(ThreadStart start);

static void Main(string[] args)
{
Thread t = new Thread(WriteY);  //创建一个新线程
t.Start(); //启动线程   WriteY
//同时，主线程也会执行。
for (int i = 0; i < 1000; i++) Console.Write("x");
Console.Read();
}

static void WriteY()
{
for (int i = 0; i < 1000; i++) Console.Write("y");
}

IsAlive

True

Thread

Name

Thread.CurrentThread

Console.Write(Thread.CurrentThread.Name);

14.2.2 联合与休眠

Join

static void Main(string[] args)
{
Thread t = new Thread(Go);
t.Start();
t.Join();
Console.WriteLine("线程 t 已经结束");
Console.Read();
}
static void Go() {   for (int i = 0; i < 1000; i++) Console.Write("y"); }

Join

Thread.Sleep(TimeSpan.FromHours(1));//休眠1小时

14.2.3 阻塞

Sleeping

Join

ThreadState

1.I/O密集与计算密集

2.阻塞与自旋

while(DateTime < nextStartTime)
Thread.Sleep(100);

14.2.4 本地状态与共享状态

static void Main(string[] args)
{
new Thread(Go).Start(); //在 新线程 上调用GO
Go();                   //在 主线程 调用GO
Console.Read();
}

static void Go()
{
for (int cycles = 0; cycles < 5; cycles++)
{
Console.Write('?');
}
}

class ThreadTest
{
bool _done;
static void Main(string[] args)
{
ThreadTest tt = new ThreadTest();
new Thread(tt.GO).Start();
tt.GO();
Console.Read();
}

void GO()
{
if (!_done)
{
_done = true;
Console.WriteLine("Done");
}
}
}

ThreadTest

14.2.5 锁与线程安全

class ThreadSafe
{
static bool _done;
static  readonly  object _locker = new object();
static void Main(string[] args)
{
new Thread(Go).Start();
Go();
Console.Read();
}

static void Go()
{
lock (_locker)
{
if (_done)
{
Console.WriteLine("Done");
_done = true;
}
}
}
}

14.2.6 传递数据到线程

static void Main()
{
Thread t = new Thread(() => Print("Hello from t!"));
t.Start();
}

static void Print(string message) { Console.WriteLine(message); }

new Thread (() =>
{
Console.WriteLine ("I'm running on another thread!");
Console.WriteLine ("This is so easy!");
}).Start()

Lambda表达式与捕获的变量

for (int i = 0; i < 10; i++)
new Thread(() => Console.Write(i)).Start();

for (int i = 0; i < 10; i++)
{
int temp = i;
new Thread (() => Console.Write (temp)).Start();
}

String text = "t1";
Thread t1 = new Thread(()=>Console.WriteLine(text));
text = "t2";
Thread t2 = new Thread(() => Console.WriteLine(text));
t1.Start();t2.Start();

14.2.7 异常处理

static void Main(string[] args)
{
try
{
new Thread(Go).Start();
}
catch (Exception)
{
//代码永远不会运行到这里
Console.WriteLine("exception");
}
}

static void Go() { throw null; } //抛出异常

Go

static void Main(string[] args)
{
new Thread(Go).Start();
}

static void Go()
{
//throw null;
try
{
throw null;//下面补货到异常 NullReferemceException
}
catch (Exception ex)
{
//通常是记录异常，并且/或者发信号给另一个线程，告诉它们捕捉到了异常
Console.WriteLine("exception");
}
}

集中式异常处理

Application.DispatcherUnhandledException

Application.ThreadException

AppDomain.CurrentDomain.UnhandledException

<configuration>
<runtime>
<legacyUnhandledExceptionPolicy enabled="1" />
</runtime>
</configuration>

14.2.8 前台线程与后台线程

IsBackground

14.2.9 线程优先级

public enum ThreadPriority
{
Lowest = 0,
BelowNormal = 1,
Normal = 2,
AboveNormal = 3,
Highest = 4,
}

System.Diagnostics

Process

worker.Priority = ThreadPriority.Highest;
//进程
using (Process p = Process.GetCurrentProcess())
{
p.PriorityClass = ProcessPriorityClass.High;
}

14.2.10 发送信号

ManualResetEvent

ManualResetEvent

WaitOne

Set

ManualResetEvent

static void Main(string[] args)
{
//通知一个或多个正在等待的线程已发生事件,如果为 true，则将初始状态设置为终止
var signal = new ManualResetEvent(false);
new Thread(() =>
{
Console.WriteLine("等待 signal..");
signal.WaitOne();  //阻止当前线程，直到当前 System.Threading.WaitHandle 收到信号
signal.Dispose();  //释放由 System.Threading.WaitHandle 类的当前实例使用的所有资源。
Console.WriteLine("开始signal");
}).Start();
Thread.Sleep(2000);
signal.Set(); //打开信号 ---（将事件状态设置为终止状态，允许一个或多个等待线程继续）

Console.Read();
}

Set

Reset

14.2.12 同步上下文

System.ComponentModel

SynchronizationContext

SynchronizationContext

SynchronizationContext.Current

BanckgroundWoker

SynchronizationContext

BanckgroundWoker

Tasks

SynchronizationContext

14.2.13 线程池

1.进入线程池

Task.Run(() => Console.WriteLine("Hello from the thread pool"));

ThreadPool.QueueUserWorkItem

ThreadPool.QueueUserWorkItem(notUsed => Console.WriteLine("Hello"));

2.线程池整洁性