ManualResetEventSlim Class
Definition
Important
Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.
Represents a thread synchronization event that, when signaled, must be reset manually. This class is a lightweight alternative to ManualResetEvent.
public ref class ManualResetEventSlim : IDisposable
public class ManualResetEventSlim : IDisposable
[System.Runtime.InteropServices.ComVisible(false)]
public class ManualResetEventSlim : IDisposable
type ManualResetEventSlim = class
interface IDisposable
[<System.Runtime.InteropServices.ComVisible(false)>]
type ManualResetEventSlim = class
interface IDisposable
Public Class ManualResetEventSlim
Implements IDisposable
- Inheritance
-
ManualResetEventSlim
- Attributes
- Implements
Examples
The following example shows how to use a ManualResetEventSlim.
using System;
using System.Threading;
using System.Threading.Tasks;
class MRESDemo
{
static void Main()
{
MRES_SetWaitReset();
MRES_SpinCountWaitHandle();
}
// Demonstrates:
// ManualResetEventSlim construction
// ManualResetEventSlim.Wait()
// ManualResetEventSlim.Set()
// ManualResetEventSlim.Reset()
// ManualResetEventSlim.IsSet
static void MRES_SetWaitReset()
{
ManualResetEventSlim mres1 = new ManualResetEventSlim(false); // initialize as unsignaled
ManualResetEventSlim mres2 = new ManualResetEventSlim(false); // initialize as unsignaled
ManualResetEventSlim mres3 = new ManualResetEventSlim(true); // initialize as signaled
// Start an asynchronous Task that manipulates mres3 and mres2
var observer = Task.Factory.StartNew(() =>
{
mres1.Wait();
Console.WriteLine("observer sees signaled mres1!");
Console.WriteLine("observer resetting mres3...");
mres3.Reset(); // should switch to unsignaled
Console.WriteLine("observer signalling mres2");
mres2.Set();
});
Console.WriteLine("main thread: mres3.IsSet = {0} (should be true)", mres3.IsSet);
Console.WriteLine("main thread signalling mres1");
mres1.Set(); // This will "kick off" the observer Task
mres2.Wait(); // This won't return until observer Task has finished resetting mres3
Console.WriteLine("main thread sees signaled mres2!");
Console.WriteLine("main thread: mres3.IsSet = {0} (should be false)", mres3.IsSet);
// It's good form to Dispose() a ManualResetEventSlim when you're done with it
observer.Wait(); // make sure that this has fully completed
mres1.Dispose();
mres2.Dispose();
mres3.Dispose();
}
// Demonstrates:
// ManualResetEventSlim construction w/ SpinCount
// ManualResetEventSlim.WaitHandle
static void MRES_SpinCountWaitHandle()
{
// Construct a ManualResetEventSlim with a SpinCount of 1000
// Higher spincount => longer time the MRES will spin-wait before taking lock
ManualResetEventSlim mres1 = new ManualResetEventSlim(false, 1000);
ManualResetEventSlim mres2 = new ManualResetEventSlim(false, 1000);
Task bgTask = Task.Factory.StartNew(() =>
{
// Just wait a little
Thread.Sleep(100);
// Now signal both MRESes
Console.WriteLine("Task signalling both MRESes");
mres1.Set();
mres2.Set();
});
// A common use of MRES.WaitHandle is to use MRES as a participant in
// WaitHandle.WaitAll/WaitAny. Note that accessing MRES.WaitHandle will
// result in the unconditional inflation of the underlying ManualResetEvent.
WaitHandle.WaitAll(new WaitHandle[] { mres1.WaitHandle, mres2.WaitHandle });
Console.WriteLine("WaitHandle.WaitAll(mres1.WaitHandle, mres2.WaitHandle) completed.");
// Clean up
bgTask.Wait();
mres1.Dispose();
mres2.Dispose();
}
}
Imports System.Threading
Imports System.Threading.Tasks
Module MRESDemo
Sub Main()
End Sub
' Demonstrates:
' ManualResetEventSlim construction
' ManualResetEventSlim.Wait()
' ManualResetEventSlim.Set()
' ManualResetEventSlim.Reset()
' ManualResetEventSlim.IsSet
Private Sub MRES_SetWaitReset()
' initialize as unsignaled
Dim mres1 As New ManualResetEventSlim(False)
' initialize as unsignaled
Dim mres2 As New ManualResetEventSlim(False)
' initialize as signaled
Dim mres3 As New ManualResetEventSlim(True)
' Start an asynchronous Task that manipulates mres3 and mres2
Dim observer = Task.Factory.StartNew(
Sub()
mres1.Wait()
Console.WriteLine("observer sees signaled mres1!")
Console.WriteLine("observer resetting mres3...")
mres3.Reset()
' should switch to unsignaled
Console.WriteLine("observer signalling mres2")
mres2.[Set]()
End Sub)
Console.WriteLine("main thread: mres3.IsSet = {0} (should be true)", mres3.IsSet)
Console.WriteLine("main thread signalling mres1")
mres1.[Set]()
' This will "kick off" the observer Task
mres2.Wait()
' This won't return until observer Task has finished resetting mres3
Console.WriteLine("main thread sees signaled mres2!")
Console.WriteLine("main thread: mres3.IsSet = {0} (should be false)", mres3.IsSet)
' make sure that observer has fully completed
observer.Wait()
' It's good form to Dispose() a ManualResetEventSlim when you're done with it
mres1.Dispose()
mres2.Dispose()
mres3.Dispose()
End Sub
' Demonstrates:
' ManualResetEventSlim construction w/ SpinCount
' ManualResetEventSlim.WaitHandle
Private Sub MRES_SpinCountWaitHandle()
' Construct a ManualResetEventSlim with a SpinCount of 1000
' Higher spincount => longer time the MRES will spin-wait before taking lock
Dim mres1 As New ManualResetEventSlim(False, 1000)
Dim mres2 As New ManualResetEventSlim(False, 1000)
Dim bgTask As Task = Task.Factory.StartNew(
Sub()
' Just wait a little
Thread.Sleep(100)
' Now signal both MRESes
Console.WriteLine("Task signalling both MRESes")
mres1.[Set]()
mres2.[Set]()
End Sub)
' A common use of MRES.WaitHandle is to use MRES as a participant in
' WaitHandle.WaitAll/WaitAny. Note that accessing MRES.WaitHandle will
' result in the unconditional inflation of the underlying ManualResetEvent.
WaitHandle.WaitAll(New WaitHandle() {mres1.WaitHandle, mres2.WaitHandle})
Console.WriteLine("WaitHandle.WaitAll(mres1.WaitHandle, mres2.WaitHandle) completed.")
' Wait for bgTask to complete and clean up
bgTask.Wait()
mres1.Dispose()
mres2.Dispose()
End Sub
End Module
Remarks
You can use this class for better performance than ManualResetEvent when wait times are expected to be very short, and when the event does not cross a process boundary. ManualResetEventSlim uses busy spinning for a short time while it waits for the event to become signaled. When wait times are short, spinning can be much less expensive than waiting by using wait handles. However, if the event does not become signaled within a certain period of time, ManualResetEventSlim resorts to a regular event handle wait.
Note
In .NET Core and .NET 5+, the default spin-waiting duration is short: on the order of 10s of microseconds, depending on platform and processor. If you expect wait times to be much longer than that, you can still use this class instead of ManualResetEvent (perhaps configured with less or no spin-waiting). However, the performance benefit would likely be only marginal.
Constructors
ManualResetEventSlim() |
Initializes a new instance of the ManualResetEventSlim class with an initial state of nonsignaled. |
ManualResetEventSlim(Boolean) |
Initializes a new instance of the ManualResetEventSlim class with a Boolean value indicating whether to set the initial state to signaled. |
ManualResetEventSlim(Boolean, Int32) |
Initializes a new instance of the ManualResetEventSlim class with a Boolean value indicating whether to set the initial state to signaled and a specified spin count. |
Properties
IsSet |
Gets whether the event is set. |
SpinCount |
Gets the number of spin waits that will occur before falling back to a kernel-based wait operation. |
WaitHandle |
Gets the underlying WaitHandle object for this ManualResetEventSlim. |
Methods
Dispose() |
Releases all resources used by the current instance of the ManualResetEventSlim class. |
Dispose(Boolean) |
Releases the unmanaged resources used by the ManualResetEventSlim, and optionally releases the managed resources. |
Equals(Object) |
Determines whether the specified object is equal to the current object. (Inherited from Object) |
GetHashCode() |
Serves as the default hash function. (Inherited from Object) |
GetType() |
Gets the Type of the current instance. (Inherited from Object) |
MemberwiseClone() |
Creates a shallow copy of the current Object. (Inherited from Object) |
Reset() |
Sets the state of the event to nonsignaled, which causes threads to block. |
Set() |
Sets the state of the event to signaled, which allows one or more threads waiting on the event to proceed. |
ToString() |
Returns a string that represents the current object. (Inherited from Object) |
Wait() |
Blocks the current thread until the current ManualResetEventSlim is set. |
Wait(CancellationToken) |
Blocks the current thread until the current ManualResetEventSlim receives a signal, while observing a CancellationToken. |
Wait(Int32) |
Blocks the current thread until the current ManualResetEventSlim is set, using a 32-bit signed integer to measure the time interval. |
Wait(Int32, CancellationToken) |
Blocks the current thread until the current ManualResetEventSlim is set, using a 32-bit signed integer to measure the time interval, while observing a CancellationToken. |
Wait(TimeSpan) |
Blocks the current thread until the current ManualResetEventSlim is set, using a TimeSpan to measure the time interval. |
Wait(TimeSpan, CancellationToken) |
Blocks the current thread until the current ManualResetEventSlim is set, using a TimeSpan to measure the time interval, while observing a CancellationToken. |
Applies to
Thread Safety
All public and protected members of ManualResetEventSlim are thread-safe and may be used concurrently from multiple threads, with the exception of Dispose, which must only be used when all other operations on the ManualResetEventSlim have completed, and Reset, which should only be used when no other threads are accessing the event.
See also
.NET