.net - MemoryFailPoint 无条件抛出 InsufficientMemoryException

Question

我有一个很奇怪的问题；在我们的 REST 应用程序中，我们引入了一个用于上传 WebPackage 的选项。由于这些在解包时可能相当大，我们希望确保通过 MemoryFailPoint 进行内存检查的成功体验。

在我的本地 IIS 7.5 上，这可以完美运行 - 甚至达到最大值。预期值为 2GB。
在我们带有 IIS 7.5 的虚拟 Windows Server 2008R2 x64 上，这会无条件地失败 - 即使只尝试 1MB。

虚拟服务器托管在 VMWare ESXi 4.1.0、348481 上。

以下是在虚拟机上失败的示例代码:

using (MemoryFailPoint failPoint = new MemoryFailPoint(1))
{
   ... // deliberately excluded webpackage code
}

和异常(exception)(在 XML 中):

<InsufficientMemoryException>
    <Message>Insufficient memory to meet the expected demands of an operation, and this system is likely to never satisfy this request.  If this is a 32 bit system, consider booting in 3 GB mode.</Message>
    <StackTrace>
        <Line>at System.Runtime.MemoryFailPoint..ctor(Int32 sizeInMegabytes)</Line>
        <Line>at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]&amp; outputs)</Line>
        <Line>at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc&amp; rpc)</Line>
        <Line>at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc&amp; rpc)</Line>
        <Line>at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31(MessageRpc&amp; rpc)</Line>
        <Line>at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)</Line>
    </StackTrace>
    <UserDefinedInformation>
        <failpointSizeInMegaBytes>1.00</failpointSizeInMegaBytes>
        <gcTotalMemoryBeforeInMegaBytes>153.34</gcTotalMemoryBeforeInMegaBytes>
    </UserDefinedInformation>
</InsufficientMemoryException>

还有一个来自我的机器的类似异常 - 请注意，我需要在触发异常之前分配 64GB :

<InsufficientMemoryException>
    <Message>Insufficient available memory to meet the expected demands of an operation at this time.  Please try again later.</Message>
    <StackTrace>
        <Line>at System.Runtime.MemoryFailPoint..ctor(Int32 sizeInMegabytes)</Line>
        <Line>at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]&amp; outputs)</Line>
        <Line>at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc&amp; rpc)</Line>
        <Line>at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc&amp; rpc)</Line>
        <Line>at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31(MessageRpc&amp; rpc)</Line>
        <Line>at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)</Line>
    </StackTrace>
    <UserDefinedInformation>
        <failpointSizeInMegaBytes>65536.00</failpointSizeInMegaBytes>
        <gcTotalMemoryBeforeInMegaBytes>150.63</gcTotalMemoryBeforeInMegaBytes>
    </UserDefinedInformation>
</InsufficientMemoryException>

这让我发疯......真的......但是嘿;请注意两个(非常)不同的异常(exception)情况:

服务器 : 内存不足，无法满足操作的预期需求，此系统很可能永远无法满足此请求。如果这是 32 位系统，请考虑以 3 GB 模式启动。

使用 Jetbrains 的 dotPeek 和这个网站 http://reflector.webtropy.com/default.aspx/4@0/4@0/untmp/DEVDIV_TFS/Dev10/Releases/RTMRel/ndp/clr/src/BCL/System/Runtime/MemoryFailPoint@cs/1305376/MemoryFailPoint@cs ，我们可以看到可能是什么问题(虽然我仍然一无所知):

        // Check to see that we both have enough memory on the system
        // and that we have enough room within the user section of the
        // process's address space.  Also, we need to use the GC segment
        // size, not the amount of memory the user wants to allocate.
        // Consider correcting this to reflect free memory within the GC
        // heap, and to check both the normal & large object heaps.
        ulong num1 = (ulong) sizeInMegabytes << 20;
        this._reservedMemory = num1;
        ulong size = (ulong)(Math.Ceiling((double)num1 / (double)MemoryFailPoint.GCSegmentSize) * (double)MemoryFailPoint.GCSegmentSize);
        if (size >= MemoryFailPoint.TopOfMemory)
            throw new InsufficientMemoryException(Environment.GetResourceString("InsufficientMemory_MemFailPoint_TooBig"));

本地 :可用内存不足，无法满足此时操作的预期需求。请稍后再试。

编辑

Hans 和我讨论了 VM 大小，但由于我现在已经得出结论，它在开发服务器和我的机器上或多或少相等，我现在将排除这部分。任何提示、建议等都非常受欢迎。

进程信息

Process Name: w3wp
PID: 5716
User Name: NT AUTHORITY\NETWORK SERVICE
Working Set: 376.456 K
Peak Working Set: 432.400 K
Private Working Set: 320.684 K
Commit Size: 538.552 K
Handles: 919
Threads: 39

操作系统 (WMI)

BootDevice: \Device\HarddiskVolume1
BuildNumber: 7601
BuildType: Multiprocessor Free
Caption: Microsoft Windows Server 2008 R2 Standard 
CodeSet: 1252
CountryCode: 45
CreationClassName: Win32_OperatingSystem
CSCreationClassName: Win32_ComputerSystem
CSDVersion: Service Pack 1
CSName: SOME_NAME [MODIFIED]
CurrentTimeZone: 120
DataExecutionPrevention_32BitApplications: True
DataExecutionPrevention_Available: True
DataExecutionPrevention_Drivers: True
DataExecutionPrevention_SupportPolicy: 3
Debug: False
Description: Development Server
Distributed: False
EncryptionLevel: 256
ForegroundApplicationBoost: 2
FreePhysicalMemory: 5.366.516 K
FreeSpaceInPagingFiles: 8.368.456 K
FreeVirtualMemory: 12.985.412 K
InstallDate: 17-01-2011 15:01:55
LargeSystemCache: null
LastBootUpTime: 11-09-2012 14:44:33
LocalDateTime: 03-10-2012 14:13:47
Locale: 0406
Manufacturer: Microsoft Corporation
MaxNumberOfProcesses: 4294967295
MaxProcessMemorySize: 8.589.934.464 K
MUILanguages: System.Object[]
Name: Microsoft Windows Server 2008 R2 Standard |C:\Windows|\Device\Harddisk0\Partition2
NumberOfLicensedUsers: null
NumberOfProcesses: 70
NumberOfUsers: 7
OperatingSystemSKU: 7
Organization: 
OSArchitecture: 64-bit
OSLanguage: 1033
OSProductSuite: 272
OSType: 18
OtherTypeDescription: null
PAEEnabled: null
PlusProductID: null
PlusVersionNumber: null
Primary: True
ProductType: 3
RegisteredUser: Windows User
SerialNumber: 11111-111-1111111-11111 [MODIFIED]
ServicePackMajorVersion: 1
ServicePackMinorVersion: 0
SizeStoredInPagingFiles: 8.388.152 K
Status: OK
SuiteMask: 272
SystemDevice: \Device\HarddiskVolume2
SystemDirectory: C:\Windows\system32
SystemDrive: C:
TotalSwapSpaceSize: null
TotalVirtualMemorySize: 16.774.452 K
TotalVisibleMemorySize: 8.388.152 K
Version: 6.1.7601
WindowsDirectory: C:\Windows

开发服务器的 VMMap 屏幕截图



出于对虚拟大小的好奇，我从 Sysinternals 下载了 VMMap: http://technet.microsoft.com/en-us/sysinternals/dd535533

我本地机器的 VMMap 屏幕截图(MemoryFailPoint 按预期工作)



我仍然不清楚 MemoryFailPoint 失败的原因 - 确保有足够的内存用于操作很重要(尤其是在讨论 Windows Azure 或其他云提供商时)。举个例子，由于资源非常有限，ExtraSmall 实例将在进程中的某个地方失败(即使它是 x64 架构)——这可以通过 MemoryFailPoint 来阻止，从而确保数据的有效状态。

非常感谢任何帮助。

Answer 1

.net 4.5 和 IIS 中存在错误(或功能)。

MemoryFailPoint 类依赖于一个内部 GC 相关变量，但在 x64 下，此变量可以为 0，除以零可以生成正无穷大(double)，并且使用此极值的某些操作(甚至与零相乘)可以生成很大的 double 值(取决于实际的 FPU 设置)。

你可以很容易地检查这个错误。
创建一个简单的 Web 应用程序并添加一个页面，然后粘贴以下代码:

<%
    var memoryFailPointType = typeof(System.Runtime.MemoryFailPoint);
    var staticPrivateFieldFlags = 
        System.Reflection.BindingFlags.NonPublic |
        System.Reflection.BindingFlags.Static;
    var gCSegmentSizeField = memoryFailPointType
        .GetField("GCSegmentSize", staticPrivateFieldFlags);
    var gCSegmentSize = (uint)gCSegmentSizeField.GetValue(null);
    string allocationResult;
    try
    {
        using (var mfp = new System.Runtime.MemoryFailPoint(1))
        {
            allocationResult = "Ok";
        }
    }
    catch (Exception exception)
    {
        allocationResult = exception.Message;
    }
%>
<%= gCSegmentSize %><br /> <!-- it can be 0 -->
<%= allocationResult %><br /> <!-- Insufficient memory to meet the expected demands of an operation, and this system is likely to never satisfy this request. If this is a 32 bit system, consider booting in 3 GB mode. -->

因此，如果 gCSegmentSize 为零且 (ulong)(double.PositiveInfinite * (uint)0) 不等于 0，则不应使用 MemoryFailPoint 类。

在控制台应用程序中，FPU 控制字是 0x09001F，但在 IIS 下，FPU 控制字是 0x08001F。