我知道CLR给每个AppDomain
ThreadPool
时间片工作,但我想,如果通过创建像这样Thread t = new Thread(...);
线程是否由线程池管理?
一个新的线程它由CLR或由AppDomin ThreadPool
设法知道吗?
我知道CLR给每个AppDomain
ThreadPool
时间片工作,但我想,如果通过创建像这样Thread t = new Thread(...);
线程是否由线程池管理?
一个新的线程它由CLR或由AppDomin ThreadPool
设法知道吗?
当您使用Thread
类创建线程时,您可以控制。您可以根据需要创建它们,并且您可以定义它们是否为background or foreground(使呼叫进程保持活动状态),您可以设置它们的Priority
,然后启动并停止它们。
随着ThreadPool
或Task
(其中使用ThreadPool
幕后)你让ThreadPool
类管理线程的创建,并最大限度地提高线程的可重用性,从而节省您创建一个新的线程所需要的时间。需要注意的一点是,与Thread
默认值不同,ThreadPool
创建的线程不会使调用进程保持活动状态。
使用ThreadPool
的一个巨大优势是可以让少量线程处理大量任务。相反,假设池没有杀死线程(因为它是为了重用而设计的),如果你有一堆由ThreadPool
创建的线程,但后来项目数量减少,则ThreadPool
闲置很多,浪费资源。
Thread t = new Thread();
将不受ThreadPool
的管理。但它是CLR在操作系统线程上提供的一种抽象。 ThreadPool是一个附加的抽象,它有助于重用线程和共享线程资源。
这里是在.NET上线的优秀资源:http://www.albahari.com/threading/
如果你使用.NET 4.0考虑使用第三方物流。
当您创建新线程时,它们是由线程池管理的而不是。
如果您手动创建线程,那么您可以控制其使用寿命,这与线程池无关。
以下示例说明如何使用线程池。它首先创建一个ManualResetEvent对象,该对象使程序能够知道线程池何时完成了所有工作项目的运行。接下来,它试图向线程池添加一个线程。如果成功,则添加其余部分(本例中为四个)。线程池然后将工作项放入可用的线程中。 eventX上的WaitOne方法被调用,这会导致程序的其余部分等待,直到触发事件(使用eventX.Set方法)。最后,程序打印线程上的加载(实际执行特定工作项的线程)。
// SimplePool.cs
// Simple thread pool example
using System;
using System.Collections;
using System.Threading;
// Useful way to store info that can be passed as a state on a work item
public class SomeState
{
public int Cookie;
public SomeState(int iCookie)
{
Cookie = iCookie;
}
}
public class Alpha
{
public Hashtable HashCount;
public ManualResetEvent eventX;
public static int iCount = 0;
public static int iMaxCount = 0;
public Alpha(int MaxCount)
{
HashCount = new Hashtable(MaxCount);
iMaxCount = MaxCount;
}
// Beta is the method that will be called when the work item is
// serviced on the thread pool.
// That means this method will be called when the thread pool has
// an available thread for the work item.
public void Beta(Object state)
{
// Write out the hashcode and cookie for the current thread
Console.WriteLine(" {0} {1} :", Thread.CurrentThread.GetHashCode(),
((SomeState)state).Cookie);
// The lock keyword allows thread-safe modification
// of variables accessible across multiple threads.
Console.WriteLine(
"HashCount.Count=={0}, Thread.CurrentThread.GetHashCode()=={1}",
HashCount.Count,
Thread.CurrentThread.GetHashCode());
lock (HashCount)
{
if (!HashCount.ContainsKey(Thread.CurrentThread.GetHashCode()))
HashCount.Add (Thread.CurrentThread.GetHashCode(), 0);
HashCount[Thread.CurrentThread.GetHashCode()] =
((int)HashCount[Thread.CurrentThread.GetHashCode()])+1;
}
// Do some busy work.
// Note: Depending on the speed of your machine, if you
// increase this number, the dispersement of the thread
// loads should be wider.
int iX = 2000;
Thread.Sleep(iX);
// The Interlocked.Increment method allows thread-safe modification
// of variables accessible across multiple threads.
Interlocked.Increment(ref iCount);
if (iCount == iMaxCount)
{
Console.WriteLine();
Console.WriteLine("Setting eventX ");
eventX.Set();
}
}
}
public class SimplePool
{
public static int Main(string[] args)
{
Console.WriteLine("Thread Pool Sample:");
bool W2K = false;
int MaxCount = 10; // Allow a total of 10 threads in the pool
// Mark the event as unsignaled.
ManualResetEvent eventX = new ManualResetEvent(false);
Console.WriteLine("Queuing {0} items to Thread Pool", MaxCount);
Alpha oAlpha = new Alpha(MaxCount); // Create the work items.
// Make sure the work items have a reference to the signaling event.
oAlpha.eventX = eventX;
Console.WriteLine("Queue to Thread Pool 0");
try
{
// Queue the work items, which has the added effect of checking
// which OS is running.
ThreadPool.QueueUserWorkItem(new WaitCallback(oAlpha.Beta),
new SomeState(0));
W2K = true;
}
catch (NotSupportedException)
{
Console.WriteLine("These API's may fail when called on a non-Windows 2000 system.");
W2K = false;
}
if (W2K) // If running on an OS which supports the ThreadPool methods.
{
for (int iItem=1;iItem < MaxCount;iItem++)
{
// Queue the work items:
Console.WriteLine("Queue to Thread Pool {0}", iItem);
ThreadPool.QueueUserWorkItem(new WaitCallback(oAlpha.Beta),new SomeState(iItem));
}
Console.WriteLine("Waiting for Thread Pool to drain");
// The call to exventX.WaitOne sets the event to wait until
// eventX.Set() occurs.
// (See oAlpha.Beta).
// Wait until event is fired, meaning eventX.Set() was called:
eventX.WaitOne(Timeout.Infinite,true);
// The WaitOne won't return until the event has been signaled.
Console.WriteLine("Thread Pool has been drained (Event fired)");
Console.WriteLine();
Console.WriteLine("Load across threads");
foreach(object o in oAlpha.HashCount.Keys)
Console.WriteLine("{0} {1}", o, oAlpha.HashCount[o]);
}
return 0;
}
}
出把
Thread Pool Sample:
Queuing 10 items to Thread Pool
Queue to Thread Pool 0
Queue to Thread Pool 1
...
...
Queue to Thread Pool 9
Waiting for Thread Pool to drain
98 0 :
HashCount.Count==0, Thread.CurrentThread.GetHashCode()==98
100 1 :
HashCount.Count==1, Thread.CurrentThread.GetHashCode()==100
98 2 :
...
...
Setting eventX
Thread Pool has been drained (Event fired)
Load across threads
101 2
100 3
98 4
102 1
我使用.NET 4.0 在面试时,我说,一个线程不是由线程池管理和组长说我错了。现在的问题是我纠正他:) – guyl
真棒链接,谢谢! –