不要将前台线程 (Foreground Threads) 和后台线程 (Background Threads)
指和常说的主线程 ( Primary Thread)和工作者线程 (Worker Thread) 混淆。
它们的定义如下 :
前台线程 (Foreground Threads): 前台线程可以阻止程序退出。除非所有前台线程都结束，否则 CLR不会关闭程序。
后台线程 (Background Threads) ： 有时候也叫 Daemon Thread 。他被 CLR 认为是不重要的执行路径，可以在任何时候舍弃。因此当所有的前台线程结束，即使还有后台线程在执行， CLR 也会关闭程序。
使用 Thread 类启动一个线程默认就是前台线程 (Foreground Threads) ，但是可以通过给 IsBackground 赋值将线程转变为后台线程。
例如 :
public class Printer
{
public void PrintNumbers()
{
// Display Thread info.
Console .WriteLine("-> {0} is executing PrintNumbers()" ,
Thread .CurrentThread.Name);
// Print out numbers.
Console .Write("Your numbers: " );
for (int i = 0; i < 10; i++)
{
Console .Write("{0}, " , i);
Thread .Sleep(2000);
}
Console .WriteLine();
}
}
static void Main(string [] args)
{
Console .WriteLine("***** Background Threads *****\n" );
Printer p = new Printer ();
Thread bgroundThread =
new Thread (new ThreadStart (p.PrintNumbers));
// This is now a background thread.
bgroundThread.IsBackground = true ;
bgroundThread.Start();
}
另外从 ThreadPool 里面去的的线程默认是后台线程 (Background Threads)
例如 :
static void Main(string [] args)
{
Console .WriteLine("***** Fun with the CLR Thread Pool *****\n" );
Console .WriteLine("Main thread started. ThreadID = {0}" ,
Thread .CurrentThread.ManagedThreadId);
Printer p = new Printer();
WaitCallback workItem = new WaitCallback (PrintTheNumbers);
// Queue the method ten times.
for (int i = 0; i < 10; i++)
{
ThreadPool .QueueUserWorkItem(workItem, p);
}
Console .WriteLine("All tasks queued" );
Console .ReadLine();
}
static void PrintTheNumbers(object state)
{
Printer task = (Printer)state;
task.PrintNumbers();
}