Windows Dev Center

Thread Class

Creates and controls a thread, and gets its status.

System.Object
  System.Threading.Thread

Namespace:  System.Threading
Assembly:  mscorlib (in mscorlib.dll)

public sealed class Thread

The Thread type exposes the following members.

  NameDescription
Public methodThread(ParameterizedThreadStart)Initializes a new instance of the Thread class, specifying a delegate that allows an object to be passed to the thread when the thread is started.
Public methodThread(ThreadStart)Initializes a new instance of the Thread class.
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  NameDescription
Public propertyCurrentCultureGets or sets the culture for the current thread.
Public propertyStatic memberCurrentThreadGets the currently running thread.
Public propertyCurrentUICultureGets or sets the current culture used by the Resource Manager to look up culture-specific resources at run time.
Public propertyIsAliveGets a value that indicates the execution status of the current thread.
Public propertyIsBackgroundGets or sets a value that indicates whether a thread is a background thread.
Public propertyManagedThreadIdGets a unique identifier for the current, managed thread.
Public propertyNameGets or sets the name of the thread.
Public propertyThreadStateGets a value that contains the states of the current thread.
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  NameDescription
Public methodAbortSecurity Critical. Raises a ThreadAbortException in the thread on which it is invoked, to begin the process of terminating the thread. Calling this method usually terminates the thread.
Public methodEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodStatic memberGetDomainReturns the current domain in which the current thread is running.
Public methodGetHashCodeReturns a hash code for the current thread. (Overrides Object.GetHashCode().)
Public methodGetTypeGets the Type of the current instance. (Inherited from Object.)
Public methodJoin()Blocks the calling thread until a thread terminates, while continuing to perform standard COM and SendMessage pumping.
Public methodJoin(Int32)Blocks the calling thread until a thread terminates or the specified time elapses, while continuing to perform standard COM and SendMessage pumping.
Protected methodMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodStatic memberMemoryBarrierEnsures that memory accesses that appear before the call to MemoryBarrier, in program order, will not execute after the call to MemoryBarrier, and that memory accesses that appear after the call to MemoryBarrier will not execute before that call.
Public methodStatic memberSleep(Int32)Suspends the current thread for a specified time.
Public methodStatic memberSleep(TimeSpan)Blocks the current thread for a specified time.
Public methodStatic memberSpinWaitCauses a thread to wait the number of times defined by the iterations parameter.
Public methodStart()Causes the operating system to change the state of the current instance to ThreadState.Running.
Public methodStart(Object)Causes the operating system to change the state of the current instance to ThreadState.Running, and optionally supplies an object containing data to be used by the method that the thread executes.
Public methodToStringReturns a string that represents the current object. (Inherited from Object.)
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A process can create one or more threads to execute portions of the program code associated with the process. The unit of execution for managed threads is the method. Use a ThreadStart delegate or the ParameterizedThreadStart delegate to specify the method executed by a thread. The ParameterizedThreadStart delegate allows you to pass data to the thread procedure as a parameter.

For the duration of its existence, a thread is always in one or more of the states defined by ThreadState.

The ManagedThreadId property provides identification for managed threads. For the lifetime of your thread, it will not collide with the value from any other thread, regardless of the application domain from which you obtain the value.

NoteNote:

An operating-system thread ID has no fixed relationship to a managed thread, because an unmanaged host can control the relationship between managed and unmanaged threads.

It is not necessary to retain a reference to a Thread object once you have started the thread. The thread continues to execute until the thread procedure is complete.

It is not necessary to create threads yourself. The BackgroundWorker and ThreadPool classes enable you to use system-managed background threads in a simple, task-oriented way. For background tasks that return results to the user interface (UI) thread, the simplest programming technique is to use the BackgroundWorker class. The following table lists some sources of information on various kinds of concurrent programming.

Task

See

Execute a background task that communicates with the main application thread by using events.

BackgroundWorker

Execute a background task that has little or no need to communicate with the main application thread.

The Managed Thread Pool

Protect regions of code or fields from concurrent access.

Monitor; the Visual Basic SyncLock statement (lock statement in C#)

Synchronize the activities of multiple threads.

EventWaitHandle, AutoResetEvent, and ManualResetEvent

Execute code in the background at regular intervals.

Timer

Execute code on the UI thread at regular intervals.

DispatcherTimer

Provide lock-free concurrent access to data.

Interlocked Operations

Create your own threads.

Thread class.

This section contains two examples. The first example shows how to create a thread that executes a static method. The second example shows how to create a thread that executes an instance method.

The examples display their output in a TextBlock on the UI thread. To access the TextBlock from the callback thread, the examples use the Dispatcher property to obtain a Dispatcher object for the TextBlock, and then use the Dispatcher.BeginInvoke method to make the cross-thread call.

For examples of coordinating the actions of threads with wait handles, see EventWaitHandle. For examples of coordinating the actions of threads with critical sections (lock in C#, SyncLock in Visual Basic), see Monitor. For examples of how to use thread pool threads, see BackgroundWorker, ThreadPool, and Timer.

Example 1

The following example shows how to create a thread that executes a static method.

NoteNote:

For information on how to compile and run this example code, see Building examples that have static TextBlock controls for Windows Phone 8.


using System;
using System.Threading;

public class Example
{
   private static System.Windows.Controls.TextBlock outputBlock;

   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      Example.outputBlock = outputBlock;

      // To start a thread using a static thread procedure, use the
      // class name and method name when you create the ThreadStart
      // delegate. C# expands the method name to the appropriate 
      // delegate creation syntax:
      //    New ThreadStart(Example.DoWork)
      //
      Thread newThread = new Thread(Example.DoWork);
      newThread.Start();
   }

   // Simulate work. To communicate with objects on the UI thread, get the 
   // Dispatcher for one of the UI objects. Use the Dispatcher object's 
   // BeginInvoke method to queue a delegate that will run on the UI thread,
   // and therefore can safely access UI elements like the TextBlock.
   private static void DoWork()
   {
      outputBlock.Dispatcher.BeginInvoke(delegate () { 
         outputBlock.Text += "Hello from a static thread procedure.\n"; 
      });
   }
}

/* This code example produces the following output:

Hello from a static thread procedure.
 */


Example 2

The following example shows how to create a thread that executes an instance method.

NoteNote:

For information on how to compile and run this example code, see Building examples that have static TextBlock controls for Windows Phone 8.


using System;
using System.Threading;

public class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      // To start a thread using an instance method for the thread 
      // procedure, use the instance variable and method name when 
      // you create the ThreadStart delegate. C# expands the object
      // reference and method name to the appropriate delegate 
      // creation syntax:
      //    New ThreadStart(AddressOf w.DoMoreWork)
      //
      Work w = new Work();
      w.Data = 42;
      w.Output = outputBlock;

      Thread newThread = new Thread(w.DoMoreWork);
      newThread.Start();
   }
}

public class Work
{
   public int Data;
   public System.Windows.Controls.TextBlock Output;

   // Simulate work. To communicate with objects on the UI thread, get the 
   // Dispatcher for one of the UI objects. Use the Dispatcher object's 
   // BeginInvoke method to queue a delegate that will run on the UI thread,
   // and therefore can safely access UI elements like the TextBlock.
   public void DoMoreWork()
   {
      Output.Dispatcher.BeginInvoke(delegate () {
         Output.Text += String.Format("Instance thread procedure. Data={0}\n", Data);
      });
   }
}

// This code example produces the following output:
//
//Instance thread procedure. Data=42


Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

This type is thread safe.

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