GCNotificationStatus Enum

Definition

Namespace:

System

Assembly:

System.Runtime.dll

Provides information about the current registration for notification of the next full garbage collection.

public enum class GCNotificationStatus

public enum GCNotificationStatus

type GCNotificationStatus = 

Public Enum GCNotificationStatus

Inheritance

Object

ValueType

Enum

GCNotificationStatus

Fields

Name	Value	Description
Succeeded	0	The notification was successful and the registration was not canceled.
Failed	1	The notification failed for any reason.
Canceled	2	The current registration was canceled by the user.
Timeout	3	The time specified by the millisecondsTimeout parameter for either WaitForFullGCApproach(Int32) or WaitForFullGCComplete(Int32) has elapsed.
NotApplicable	4	This value can result when there's no current registration for a garbage collection notification, or a full GC has happened but was done as a background GC (that is, a GC that runs mostly concurrently with user threads) instead of a full blocking GC. Background GC is enabled by default; disabling it improves the prediction accuracy but incurs larger GC pauses.

Examples

The following example obtains a GCNotificationStatus enumeration from the WaitForFullGCApproach method. If the enumeration returns Succeeded, it calls the custom method OnFullGCApproachNotify to perform actions in response to the approaching full garbage collection. This code example is part of a larger example provided for Garbage Collection Notifications topic.

public:
    static void WaitForFullGCProc()
    {
        while (true)
        {
            // CheckForNotify is set to true and false in Main.
            while (checkForNotify)
            {
                // Check for a notification of an approaching collection.
                GCNotificationStatus s = GC::WaitForFullGCApproach();
                if (s == GCNotificationStatus::Succeeded)
                {
                    Console::WriteLine("GC Notifiction raised.");
                    OnFullGCApproachNotify();
                }
                else if (s == GCNotificationStatus::Canceled)
                {
                    Console::WriteLine("GC Notification cancelled.");
                    break;
                }
                else
                {
                    // This can occur if a timeout period
                    // is specified for WaitForFullGCApproach(Timeout)
                    // or WaitForFullGCComplete(Timeout)
                    // and the time out period has elapsed.
                    Console::WriteLine("GC Notification not applicable.");
                    break;
                }

                // Check for a notification of a completed collection.
                s = GC::WaitForFullGCComplete();
                if (s == GCNotificationStatus::Succeeded)
                {
                    Console::WriteLine("GC Notification raised.");
                    OnFullGCCompleteEndNotify();
                }
                else if (s == GCNotificationStatus::Canceled)
                {
                    Console::WriteLine("GC Notification cancelled.");
                    break;
                }
                else
                {
                    // Could be a time out.
                    Console::WriteLine("GC Notification not applicable.");
                    break;
                }
            }


            Thread::Sleep(500);
            // FinalExit is set to true right before
            // the main thread cancelled notification.
            if (finalExit)
            {
                break;
            }
        }
    }

public static void WaitForFullGCProc()
{
    while (true)
    {
        // CheckForNotify is set to true and false in Main.
        while (checkForNotify)
        {
            // Check for a notification of an approaching collection.
            GCNotificationStatus s = GC.WaitForFullGCApproach();
            if (s == GCNotificationStatus.Succeeded)
            {
                Console.WriteLine("GC Notification raised.");
                OnFullGCApproachNotify();
            }
            else if (s == GCNotificationStatus.Canceled)
            {
                Console.WriteLine("GC Notification cancelled.");
                break;
            }
            else
            {
                // This can occur if a timeout period
                // is specified for WaitForFullGCApproach(Timeout)
                // or WaitForFullGCComplete(Timeout)
                // and the time out period has elapsed.
                Console.WriteLine("GC Notification not applicable.");
                break;
            }

            // Check for a notification of a completed collection.
            GCNotificationStatus status = GC.WaitForFullGCComplete();
            if (status == GCNotificationStatus.Succeeded)
            {
                Console.WriteLine("GC Notification raised.");
                OnFullGCCompleteEndNotify();
            }
            else if (status == GCNotificationStatus.Canceled)
            {
                Console.WriteLine("GC Notification cancelled.");
                break;
            }
            else
            {
                // Could be a time out.
                Console.WriteLine("GC Notification not applicable.");
                break;
            }
        }

        Thread.Sleep(500);
        // FinalExit is set to true right before
        // the main thread cancelled notification.
        if (finalExit)
        {
            break;
        }
    }
}

let waitForFullGCProc () =
    let mutable broken = false

    while not broken do
        let mutable broken = false
        // CheckForNotify is set to true and false in Main.
        while checkForNotify && not broken do
            // Check for a notification of an approaching collection.
            match GC.WaitForFullGCApproach() with
            | GCNotificationStatus.Succeeded ->
                printfn "GC Notification raised."
                onFullGCApproachNotify ()
                // Check for a notification of a completed collection.
                match GC.WaitForFullGCComplete() with
                | GCNotificationStatus.Succeeded ->
                    printfn "GC Notification raised."
                    onFullGCCompleteEndNotify ()
                | GCNotificationStatus.Canceled ->
                    printfn "GC Notification cancelled."
                    broken <- true
                | _ ->
                    // Could be a time out.
                    printfn "GC Notification not applicable."
                    broken <- true
            | GCNotificationStatus.Canceled ->
                printfn "GC Notification cancelled."
                broken <- true
            | _ ->
                // This can occur if a timeout period
                // is specified for WaitForFullGCApproach(Timeout)
                // or WaitForFullGCComplete(Timeout)
                // and the time out period has elapsed.
                printfn "GC Notification not applicable."
                broken <- true

        Thread.Sleep 500
        // FinalExit is set to true right before
        // the main thread cancelled notification.
        if finalExit then broken <- true

Public Shared Sub WaitForFullGCProc()

    While True
        ' CheckForNotify is set to true and false in Main.

        While checkForNotify
            ' Check for a notification of an approaching collection.
            Dim s As GCNotificationStatus = GC.WaitForFullGCApproach
            If (s = GCNotificationStatus.Succeeded) Then
                Console.WriteLine("GC Notification raised.")
                OnFullGCApproachNotify()
            ElseIf (s = GCNotificationStatus.Canceled) Then
                Console.WriteLine("GC Notification cancelled.")
                Exit While
            Else
                ' This can occur if a timeout period
                ' is specified for WaitForFullGCApproach(Timeout) 
                ' or WaitForFullGCComplete(Timeout)  
                ' and the time out period has elapsed. 
                Console.WriteLine("GC Notification not applicable.")
                Exit While
            End If

            ' Check for a notification of a completed collection.
            s = GC.WaitForFullGCComplete
            If (s = GCNotificationStatus.Succeeded) Then
                Console.WriteLine("GC Notifiction raised.")
                OnFullGCCompleteEndNotify()
            ElseIf (s = GCNotificationStatus.Canceled) Then
                Console.WriteLine("GC Notification cancelled.")
                Exit While
            Else
                ' Could be a time out.
                Console.WriteLine("GC Notification not applicable.")
                Exit While
            End If

        End While
        Thread.Sleep(500)
        ' FinalExit is set to true right before  
        ' the main thread cancelled notification.
        If finalExit Then
            Exit While
        End If

    End While
End Sub

Remarks

Use the RegisterForFullGCNotification method to register for a full garbage collection notification. Then use the WaitForFullGCApproach method or the WaitForFullGCComplete method to return a GCNotificationStatus enumeration that contains the status of the notification.

See also

• Garbage Collection Notifications