WaitAll Method (WaitHandle[], Int32)
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WaitHandle.WaitAll Method (WaitHandle(), Int32)

[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]

Waits for all the elements in the specified array to receive a signal, using an Int32 value to specify the time interval.

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

Public Shared Function WaitAll ( _
	waitHandles As WaitHandle(), _
	millisecondsTimeout As Integer _
) As Boolean


Type: System.Threading.WaitHandle ()
An array that contains the objects for which the current instance will wait. This array cannot contain multiple references to the same object.
Type: System.Int32
The number of milliseconds to wait, or Timeout.Infinite (-1) to wait indefinitely.

Return Value

Type: System.Boolean
true when every element in waitHandles has received a signal; otherwise, false.


The waitHandles parameter is Nothing. -or-

One or more of the objects in the waitHandles array is Nothing.


The waitHandles array contains elements that are duplicates.


waitHandles is an array with no elements.


The number of objects in waitHandles is greater than the system permits.


millisecondsTimeout is a negative number other than -1, which represents an infinite time-out.

If millisecondsTimeout is zero, the method does not block. It tests the state of the wait handles and returns immediately.

The WaitAll method returns when the wait terminates, either when all the handles are signaled or when a time-out occurs. On some implementations, if more than 64 handles are passed, a NotSupportedException is thrown. If there are duplicates in the array, the call fails with an ArgumentException.

If you call this method from a single-threaded apartment, and waitHandles contains more than one wait handle, the method deadlocks.

Version Notes

Windows Phone

 WaitAll is present but not supported in Windows Phone.

The following example shows how to use this overload of the WaitAll method to report progress while waiting for multiple threads to finish. Each time the WaitAll method times out, the thread that was waiting reports progress to the user interface thread.

This code is part of a larger example provided for the WaitHandle class.

' Wait for ALL subtasks to complete, and show progress every 1/4 second if
' the WaitAll times out.

While Not WaitHandle.WaitAll(waitHandles, 250)

   ' If the WaitAll timed out, show progress.

End While

Windows Phone OS

Supported in: 8.1, 8.0, 7.1, 7.0

Windows Phone

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