GC.RegisterForFullGCNotification(Int32, Int32) 方法
定義
重要
部分資訊涉及發行前產品，在發行之前可能會有大幅修改。 Microsoft 對此處提供的資訊，不做任何明確或隱含的瑕疵擔保。
指定當情況需要完整記憶體回收時和回收完成時，應引發記憶體回收通知。
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 -> unitPublic Shared Sub RegisterForFullGCNotification (maxGenerationThreshold As Integer, largeObjectHeapThreshold As Integer)參數
- maxGenerationThreshold
- Int32
範圍從 1 到 99 的數字，指定何時應根據層代 2 中所配置的物件加以引發通知。
- largeObjectHeapThreshold
- Int32
範圍從 1 到 99 的數字，指定何時根據大型物件堆積中所配置的物件加以引發通知。
- 屬性
例外狀況
maxGenerationThreshold 或 largeObjectHeapThreshold 未介於 1 和 99 之間。
啟用並行記憶體回收時，無法使用這個成員。 如需如何停用並行記憶體回收的資訊，請參閱 <gcConcurrent> 執行階段設定。
範例
下列範例示範如何註冊垃圾收集通知，並啟動執行緒來監視垃圾收集通知的狀態。 此程式碼範例是針對 垃圾收集通知 主題所提供的較大範例的一部分。
using namespace System;
using namespace System::Collections::Generic;
using namespace System::Threading;
namespace GCNotify
{
ref class Program
{
private:
// 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<array<Byte>^>^ load = gcnew List<array<Byte>^>();
public:
static void Main()
{
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 = gcnew Thread(gcnew 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(gcnew array<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 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;
}
}
}
private:
static void RedirectRequests()
{
// Code that sends requests
// to other servers.
// Suspend work.
bAllocate = false;
}
static void FinishExistingRequests()
{
// Code that waits a period of time
// for pending requests to finish.
// Clear the simulated workload.
load->Clear();
}
static void AcceptRequests()
{
// Code that resumes processing
// requests on this server.
// Resume work.
bAllocate = true;
}
};
}
int main()
{
GCNotify::Program::Main();
}
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
備註
針對每個產生，垃圾收集行程會針對該產生中的配置設定臨界值。 當配置大小超過此臨界值時，就會在該產生時觸發垃圾收集。 例如，如果層代 2 的閾值為 20MB (這表示 20 MB 在層代 1 集合中存留，並升階為層代 2) ，而超過 20MB 在層代 1 中存留，並提示到層代 2，則會嘗試下一個垃圾收集作為層代 2 回收。 同樣地，如果大型物件堆積 (LOH 的) 閾值是 20 MB，且您的應用程式已配置超過 20 MB 的大型物件，則下一個垃圾收集也會嘗試作為層代 2 收集 (，因為 LOH 只會在 gen2 垃圾收集中收集) 。
maxGenerationThreshold和 largeObjectHeapThreshold 臨界值可控制在發生完整垃圾收集之前，您事先收到多少通知。 臨界值愈大，通知與下一個完整垃圾收集之間可能發生的配置越多。
如果您遇到 Common Language Runtime 的完整垃圾收集會對應用程式的效能造成負面影響的情況，您可以在執行時間即將執行完整垃圾收集時要求收到通知，並藉由使用方法自行 Collect (收集來規避該收集，) 條件仍然可行時，自行規避該收集。 除了自行變更垃圾收集排程之外，完整 GC 通知在下列案例中很有用：
您可以監視完整垃圾收集的方法，當您收到通知時，您可以藉由釋放某些快取專案) 來減少即時資料大小 (。 因此，當垃圾收集發生時，就能夠回收更多記憶體。
您可以監視完整垃圾收集的完成，以便收集一些統計資料。 例如，您可能想要在 GC 完成時測量堆積的大小，以便知道即時資料的大小。 (完整 GC 之後，堆積的大小會最小。)
如需代表完整垃圾收集之專案的詳細資訊，請參閱 垃圾收集通知。
當您註冊垃圾收集通知時，您可以在完整垃圾收集接近時以及完成時收到通知。 此模式類似于作業系統如何監視低記憶體通知。
使用下列指導方針來指定 maxGenerationThreshold 和 largeObjectHeapThreshold 參數：
閾值愈大，通知與完整垃圾收集之間的配置就會愈多。
較大的閾值可為執行時間提供更多機會來檢查接近的集合。 這會增加您會收到通知的可能性。 不過，您不應該設定臨界值太高，因為這會導致執行時間引發下一個集合之前的更多配置。
當您使用高臨界值在通知時自行引發集合時，回收的物件會比執行時間的下一個集合回收少。
臨界值越小，通知與完整垃圾收集之間的配置就越少。
