GC.RegisterForFullGCNotification(Int32, Int32) メソッド

public:
 static void RegisterForFullGCNotification(int maxGenerationThreshold, int largeObjectHeapThreshold);

public static void RegisterForFullGCNotification(int maxGenerationThreshold, int largeObjectHeapThreshold);

[System.Security.SecurityCritical]
public static void RegisterForFullGCNotification(int maxGenerationThreshold, int largeObjectHeapThreshold);

static member RegisterForFullGCNotification : int * int -> unit

[<System.Security.SecurityCritical>]
static member RegisterForFullGCNotification : int * int -> unit

Public Shared Sub RegisterForFullGCNotification (maxGenerationThreshold As Integer, largeObjectHeapThreshold As Integer)

パラメーター

属性

SecurityCriticalAttribute

例外

例

次の例は、ガベージ コレクション通知を登録し、スレッドを開始してガベージ コレクション通知の状態を監視する方法を示しています。 このコード例は、 ガベージ コレクション通知 に関するトピックで提供されるより大きな例の一部です。

using System;
using System.Collections.Generic;
using System.Threading;

namespace GCNotify
{
    class Program
    {
        // Variable for continual checking in the
        // While loop in the WaitForFullGCProc method.
        static bool checkForNotify = false;

        // Variable for suspending work
        // (such servicing allocated server requests)
        // after a notification is received and then
        // resuming allocation after inducing a garbage collection.
        static bool bAllocate = false;

        // Variable for ending the example.
        static bool finalExit = false;

        // Collection for objects that
        // simulate the server request workload.
        static List<byte[]> load = new List<byte[]>();

        public static void Main(string[] args)
        {
            try
            {
                // Register for a notification.
                GC.RegisterForFullGCNotification(10, 10);
                Console.WriteLine("Registered for GC notification.");

                checkForNotify = true;
                bAllocate = true;

                // Start a thread using WaitForFullGCProc.
                Thread thWaitForFullGC = new Thread(new ThreadStart(WaitForFullGCProc));
                thWaitForFullGC.Start();

                // While the thread is checking for notifications in
                // WaitForFullGCProc, create objects to simulate a server workload.
                try
                {

                    int lastCollCount = 0;
                    int newCollCount = 0;

                    while (true)
                    {
                        if (bAllocate)
                        {
                            load.Add(new byte[1000]);
                            newCollCount = GC.CollectionCount(2);
                            if (newCollCount != lastCollCount)
                            {
                                // Show collection count when it increases:
                                Console.WriteLine("Gen 2 collection count: {0}", GC.CollectionCount(2).ToString());
                                lastCollCount = newCollCount;
                            }

                            // For ending the example (arbitrary).
                            if (newCollCount == 500)
                            {
                                finalExit = true;
                                checkForNotify = false;
                                break;
                            }
                        }
                    }
                }
                catch (OutOfMemoryException)
                {
                    Console.WriteLine("Out of memory.");
                }

                finalExit = true;
                checkForNotify = false;
                GC.CancelFullGCNotification();
            }
            catch (InvalidOperationException invalidOp)
            {

                Console.WriteLine("GC Notifications are not supported while concurrent GC is enabled.\n"
                    + invalidOp.Message);
            }
        }

        public static void OnFullGCApproachNotify()
        {

            Console.WriteLine("Redirecting requests.");

            // Method that tells the request queuing
            // server to not direct requests to this server.
            RedirectRequests();

            // Method that provides time to
            // finish processing pending requests.
            FinishExistingRequests();

            // This is a good time to induce a GC collection
            // because the runtime will induce a full GC soon.
            // To be very careful, you can check precede with a
            // check of the GC.GCCollectionCount to make sure
            // a full GC did not already occur since last notified.
            GC.Collect();
            Console.WriteLine("Induced a collection.");
        }

        public static void OnFullGCCompleteEndNotify()
        {
            // Method that informs the request queuing server
            // that this server is ready to accept requests again.
            AcceptRequests();
            Console.WriteLine("Accepting requests again.");
        }

        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;
                }
            }
        }

        private static void RedirectRequests()
        {
            // Code that sends requests
            // to other servers.

            // Suspend work.
            bAllocate = false;
        }

        private static void FinishExistingRequests()
        {
            // Code that waits a period of time
            // for pending requests to finish.

            // Clear the simulated workload.
            load.Clear();
        }

        private static void AcceptRequests()
        {
            // Code that resumes processing
            // requests on this server.

            // Resume work.
            bAllocate = true;
        }
    }
}

open System
open System.Threading

// Variable for continual checking in the
// While loop in the WaitForFullGCProc method.
let mutable checkForNotify = false

// Variable for suspending work
// (such servicing allocated server requests)
// after a notification is received and then
// resuming allocation after inducing a garbage collection.
let mutable bAllocate = false

// Variable for ending the example.
let mutable finalExit = false

// Collection for objects that simulate the server request workload.
let load = ResizeArray<byte []>()


let redirectRequests () =
    // Code that sends requests
    // to other servers.

    // Suspend work.
    bAllocate <- false

let finishExistingRequests () =
    // Code that waits a period of time
    // for pending requests to finish.

    // Clear the simulated workload.
    load.Clear()

let acceptRequests () =
    // Code that resumes processing
    // requests on this server.

    // Resume work.
    bAllocate <- true

let onFullGCApproachNotify () =
    printfn "Redirecting requests."

    // Method that tells the request queuing
    // server to not direct requests to this server.
    redirectRequests ()

    // Method that provides time to
    // finish processing pending requests.
    finishExistingRequests ()

    // This is a good time to induce a GC collection
    // because the runtime will induce a full GC soon.
    // To be very careful, you can check precede with a
    // check of the GC.GCCollectionCount to make sure
    // a full GC did not already occur since last notified.
    GC.Collect()
    printfn "Induced a collection."


let onFullGCCompleteEndNotify () =
    // Method that informs the request queuing server
    // that this server is ready to accept requests again.
    acceptRequests ()
    printfn "Accepting requests again."

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



try
    // Register for a notification.
    GC.RegisterForFullGCNotification(10, 10)
    printfn "Registered for GC notification."

    checkForNotify <- true
    bAllocate <- true

    // Start a thread using WaitForFullGCProc.
    let thWaitForFullGC = Thread(ThreadStart waitForFullGCProc)
    thWaitForFullGC.Start()

    // While the thread is checking for notifications in
    // WaitForFullGCProc, create objects to simulate a server workload.
    try
        let mutable lastCollCount = 0
        let mutable newCollCount = 0

        let mutable broken = false

        while not broken do
            if bAllocate then
                load.Add(Array.zeroCreate<byte> 1000)
                newCollCount <- GC.CollectionCount 2

                if newCollCount <> lastCollCount then
                    // Show collection count when it increases:
                    printfn $"Gen 2 collection count: {GC.CollectionCount(2)}"
                    lastCollCount <- newCollCount
                // For ending the example (arbitrary).
                if newCollCount = 500 then
                    finalExit <- true
                    checkForNotify <- false
                    broken <- true
    with :? OutOfMemoryException -> printfn "Out of memory."

    finalExit <- true
    checkForNotify <- false
    GC.CancelFullGCNotification()
with :? InvalidOperationException as invalidOp ->
    printfn $"GC Notifications are not supported while concurrent GC is enabled.\n{invalidOp.Message}"

Imports System.Collections.Generic
Imports System.Threading

Class Program
    ' Variables for continual checking in the
    ' While loop in the WaitForFullGcProc method.
    Private Shared checkForNotify As Boolean = False

    ' Variable for suspending work 
    ' (such as servicing allocated server requests)
    ' after a notification is received and then 
    ' resuming allocation after inducing a garbage collection.
    Private Shared bAllocate As Boolean = False

    ' Variable for ending the example.
    Private Shared finalExit As Boolean = False

    ' Collection for objects that  
    ' simulate the server request workload.
    Private Shared load As New List(Of Byte())


    Public Shared Sub Main(ByVal args() As String)
        Try
            ' Register for a notification. 
            GC.RegisterForFullGCNotification(10, 10)
            Console.WriteLine("Registered for GC notification.")

            bAllocate = True
            checkForNotify = True

            ' Start a thread using WaitForFullGCProc.
            Dim thWaitForFullGC As Thread = _
                New Thread(New ThreadStart(AddressOf WaitForFullGCProc))
            thWaitForFullGC.Start()

            ' While the thread is checking for notifications in
            ' WaitForFullGCProc, create objects to simulate a server workload.
            Try
                Dim lastCollCount As Integer = 0
                Dim newCollCount As Integer = 0
                
                
                While (True)
                    If bAllocate = True Then

                        load.Add(New Byte(1000) {})
                        newCollCount = GC.CollectionCount(2)
                        If (newCollCount <> lastCollCount) Then
                            ' Show collection count when it increases:
                            Console.WriteLine("Gen 2 collection count: {0}", _
                                              GC.CollectionCount(2).ToString)
                            lastCollCount = newCollCount
                        End If

                        ' For ending the example (arbitrary).
                        If newCollCount = 500 Then
                            finalExit = True
                            checkForNotify = False
                            bAllocate = False
                            Exit While
                        End If

                    End If
                End While
                
            Catch outofMem As OutOfMemoryException
                Console.WriteLine("Out of memory.")
            End Try

            finalExit = True
            checkForNotify = False
            GC.CancelFullGCNotification()

        Catch invalidOp As InvalidOperationException
            Console.WriteLine("GC Notifications are not supported while concurrent GC is enabled." _
                              & vbLf & invalidOp.Message)
        End Try
    End Sub

    Public Shared Sub OnFullGCApproachNotify()
        Console.WriteLine("Redirecting requests.")

        ' Method that tells the request queuing  
        ' server to not direct requests to this server. 
        RedirectRequests()

        ' Method that provides time to 
        ' finish processing pending requests. 
        FinishExistingRequests()

        ' This is a good time to induce a GC collection
        ' because the runtime will induce a ful GC soon.
        ' To be very careful, you can check precede with a
        ' check of the GC.GCCollectionCount to make sure
        ' a full GC did not already occur since last notified.
        GC.Collect()
        Console.WriteLine("Induced a collection.")
    End Sub

    Public Shared Sub OnFullGCCompleteEndNotify()
        ' Method that informs the request queuing server
        ' that this server is ready to accept requests again.
        AcceptRequests()
        Console.WriteLine("Accepting requests again.")
    End Sub

    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

    Private Shared Sub RedirectRequests()
        ' Code that sends requests
        ' to other servers.

        ' Suspend work.
        bAllocate = False
    End Sub

    Private Shared Sub FinishExistingRequests()
        ' Code that waits a period of time
        ' for pending requests to finish.

        ' Clear the simulated workload.
        load.Clear()

    End Sub

    Private Shared Sub AcceptRequests()
        ' Code that resumes processing
        ' requests on this server.

        ' Resume work.
        bAllocate = True
    End Sub
End Class

注釈

ガベージ コレクターは、世代ごとに、その世代への割り当てのしきい値を設定します。 割り当てのサイズがこのしきい値を超えると、その世代でガベージ コレクションがトリガーされます。 たとえば、ジェネレーション 2 のしきい値が 20 MB の場合 (つまり、20 MB はジェネレーション 1 のコレクションで存続し、ジェネレーション 2 に昇格されます)、20 MB を超える場合はジェネレーション 1 が存続し、ジェネレーション 2 に求められます。次のガベージ コレクションはジェネレーション 2 コレクションとして試行されます。 同様に、ラージ オブジェクト ヒープ (LOH) のしきい値が 20 MB で、アプリで 20 MB を超えるラージ オブジェクトが割り当てられている場合、次のガベージ コレクションもジェネレーション 2 コレクションとして試行されます (LOH は gen2 ガベージ コレクションでのみ収集されるため)。

maxGenerationThresholdとlargeObjectHeapThresholdのしきい値は、完全なガベージ コレクションが発生する前に通知を受け取る量を制御します。 しきい値が大きいほど、通知と次のフル ガベージ コレクションの間で発生する可能性のある割り当てが増えます。

共通言語ランタイムによるフル ガベージ コレクションがアプリケーションのパフォーマンスに悪影響を与える状況がある場合は、ランタイムがフル ガベージ コレクションを実行しようとしているときに通知を受け取り、条件がまだ良好な場合に ( Collect メソッドを使用して) コレクションを自分で誘導して、そのコレクションを回避するように求めることができます。 ガベージ コレクションのスケジュールを自分で変更するだけでなく、完全な GC 通知は次のシナリオで役立ちます。

• フル ガベージ コレクションのアプローチを監視し、近づいていることが通知されたら、ライブ データ サイズを小さくします (たとえば、キャッシュ エントリを解放します)。 その結果、ガベージ コレクションが発生すると、より多くのメモリを再利用できます。

• 一部の統計を収集できるように、フル ガベージ コレクションの完了を監視します。 たとえば、GC の完了時にヒープのサイズを測定して、ライブ データのサイズを把握することができます。 (完全な GC の後、ヒープのサイズは最小になります)。

フル ガベージ コレクションを表す内容の詳細については、「 ガベージ コレクションの通知」を参照してください。

ガベージ コレクション通知に登録すると、フル ガベージ コレクションが近づいているとき、および完了したときに通知を受け取ることができます。 このパターンは、オペレーティング システムがメモリ不足の通知を監視する方法に似ています。

maxGenerationThresholdパラメーターとlargeObjectHeapThreshold パラメーターを指定するには、次のガイドラインを使用します。

• しきい値が大きいほど、通知と完全なガベージ コレクションの間でより多くの割り当てが行われます。

  しきい値を大きくすると、近づいているコレクションをランタイムがチェックする機会が増えます。 これにより、通知を受け取る可能性が高くなります。 ただし、しきい値を高く設定しすぎないようにしてください。これは、ランタイムが次のコレクションを誘発する前に割り当てが増えるためです。

  高いしきい値を使用して通知時にコレクションを自分で誘発すると、ランタイムの次のコレクションによって回収されるオブジェクトよりも少ないオブジェクトが再利用されます。

• しきい値が小さいと、通知と完全なガベージ コレクションの間の割り当てが少なくなります。

こちらもご覧ください

• ガベージ コレクションの通知