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Thread.SpinWait(Int32) Method


Causes a thread to wait the number of times defined by the iterations parameter.

 static void SpinWait(int iterations);
public static void SpinWait (int iterations);
static member SpinWait : int -> unit
Public Shared Sub SpinWait (iterations As Integer)



A 32-bit signed integer that defines how long a thread is to wait.


The SpinWait method is useful for implementing locks. Classes in the .NET Framework, such as Monitor and ReaderWriterLock, use this method internally. SpinWait essentially puts the processor into a very tight loop, with the loop count specified by the iterations parameter. The duration of the wait therefore depends on the speed of the processor.

Contrast this with the Sleep method. A thread that calls Sleep yields the rest of its current slice of processor time, even if the specified interval is zero. Specifying a non-zero interval for Sleep removes the thread from consideration by the thread scheduler until the time interval has elapsed.

SpinWait is not generally useful for ordinary applications. In most cases, you should use the synchronization classes provided by the .NET Framework; for example, call Monitor.Enter or a statement that wraps Monitor.Enter (lock in C# or SyncLock in Visual Basic).


In the rare case where it is advantageous to avoid a context switch, such as when you know that a state change is imminent, make a call to the SpinWait method in your loop. The code SpinWait executes is designed to prevent problems that can occur on computers with multiple processors. For example, on computers with multiple Intel processors employing Hyper-Threading technology, SpinWait prevents processor starvation in certain situations.

Applies to