WaitHandle.WaitAny Method (WaitHandle[], TimeSpan)

Waits for any of the elements in the specified array to receive a signal, using a TimeSpan to specify the time interval.

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

public static int WaitAny(
	WaitHandle[] waitHandles,
	TimeSpan timeout


Type: System.Threading.WaitHandle[]
An array that contains the objects for which the current instance will wait.
Type: System.TimeSpan
A TimeSpan that represents the number of milliseconds to wait, or a TimeSpan that represents -1 milliseconds to wait indefinitely.

Return Value

Type: System.Int32
The array index of the object that satisfied the wait, or WaitTimeout if no object satisfied the wait and a time interval equivalent to timeout has passed.


The waitHandles parameter is null.


One or more of the objects in the waitHandles array is null.


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


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


timeout is greater than Int32.MaxValue.


waitHandles is an array with no elements.

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

This method returns when the wait terminates, either when any of the handles are signaled or when a time-out occurs. If more than one object becomes signaled during the call, the return value is the array index of the signaled object with the smallest index value of all the signaled objects. On some implementations, if more that 64 handles are passed, a NotSupportedException is thrown.

The maximum value for timeout is Int32.MaxValue.

The following example shows how to use this overload of the WaitAny method to report progress while waiting for multiple threads to finish. Each time the WaitAny 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 WaitAll(WaitHandle[], TimeSpan) method overload.

// Wait for ANY subtask to complete, and show progress.

// Create an array of ManualResetEvent wait handles. Each subtask will
// signal its ManualResetEvent when it is finished.
WaitHandle[] waitHandles = finished.ToArray();
int index = WaitHandle.WaitTimeout;

while (index == WaitHandle.WaitTimeout)
   // Wait for any WaitHandle to be signaled. Use a timeout of 250 milliseconds 
   // to send progress reports. If a timeout occurs, WaitTimeout is returned;
   // if a WaitHandle signals, the array index of the WaitHandle is returned.
   index = WaitHandle.WaitAny(waitHandles, new TimeSpan(0, 0, 0, 0, 250));


Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

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