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Thread.Join Method (TimeSpan)

Blocks the calling thread until a thread terminates or the specified time elapses, while continuing to perform standard COM and SendMessage pumping.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true, 
	ExternalThreading = true)]
public bool Join(
	TimeSpan timeout
)

Parameters

timeout
Type: System.TimeSpan

A TimeSpan set to the amount of time to wait for the thread to terminate.

Return Value

Type: System.Boolean
true if the thread terminated; false if the thread has not terminated after the amount of time specified by the timeout parameter has elapsed.

ExceptionCondition
ArgumentOutOfRangeException

The value of timeout is negative and is not equal to Timeout.Infinite in milliseconds, or is greater than Int32.MaxValue milliseconds.

ThreadStateException

The caller attempted to join a thread that is in the Unstarted state.

Join(TimeSpan) is a synchronization method that blocks the calling thread (that is, the thread that calls the method) until either the thread whose Join method is called has completed or the time-out interval has elapsed. In the following example, the Thread1 thread calls the Join() method of Thread2, which causes Thread1 to block either until Thread2 has completed or 2 seconds have elapsed.

using System;
using System.Threading;

public class Example
{
   static Thread mainThread, thread1, thread2;

   public static void Main()
   {
      mainThread = Thread.CurrentThread;
      thread1 = new Thread(ThreadProc);
      thread1.Name = "Thread1";
      thread1.Start();

      thread2 = new Thread(ThreadProc);
      thread2.Name = "Thread2";
      thread2.Start();   
   }

   private static void ThreadProc()
   {
      Console.WriteLine("\nCurrent thread: {0}", Thread.CurrentThread.Name);
      if (Thread.CurrentThread.Name == "Thread1" && 
          thread2.ThreadState != ThreadState.Unstarted)
         if (thread2.Join(TimeSpan.FromSeconds(2)))
            Console.WriteLine("Thread2 has termminated.");
         else
            Console.WriteLine("The timeout has elapsed and Thread1 will resume.");   

      Thread.Sleep(4000);
      Console.WriteLine("\nCurrent thread: {0}", Thread.CurrentThread.Name);
      Console.WriteLine("Thread1: {0}", thread1.ThreadState);
      Console.WriteLine("Thread2: {0}\n", thread2.ThreadState);
   }
}
// The example displays the following output: 
//       Current thread: Thread1 
//        
//       Current thread: Thread2 
//       The timeout has elapsed and Thread1 will resume. 
//        
//       Current thread: Thread2 
//       Thread1: WaitSleepJoin 
//       Thread2: Running 
//        
//        
//       Current thread: Thread1 
//       Thread1: Running 
//       Thread2: Stopped

If Timeout.Infinite is specified for timeout, this method behaves identically to the Join() method overload, except for the return value.

If the thread has already terminated when Join is called, the method returns immediately.

This method changes the state of the current thread to include WaitSleepJoin. You cannot invoke Join on a thread that is in the ThreadState.Unstarted state.

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization | ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following code example demonstrates how to use a TimeSpan value with the Join method.

using System;
using System.Threading;

class Test
{
    static TimeSpan waitTime = new TimeSpan(0, 0, 1);

    public static void Main() 
    {
        Thread newThread = new Thread(Work);
        newThread.Start();

        if(newThread.Join(waitTime + waitTime)) {
            Console.WriteLine("New thread terminated.");
        }
        else {
            Console.WriteLine("Join timed out.");
        }
    }

    static void Work()
    {
        Thread.Sleep(waitTime);
    }
}
// The example displays the following output: 
//        New thread terminated.

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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