间歇性无法加载文件或程序集/策略异常

间歇性地,我们会从.NET3.5Web应用程序中得到如下错误:

Exception:
System.Configuration.ConfigurationErrorsException: Could not load file or assembly 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418) (C:\Windows\Microsoft.NET\Framework64\v2.0.50727\Config\web.config line 59) ---> System.IO.FileLoadException: Could not load file or assembly 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418) File name: 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' ---> System.Security.Policy.PolicyException: Execution permission cannot be acquired.
   at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission)
   at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission)
   at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection)
   at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.Load(String assemblyString)
   at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)


   --- End of inner exception stack trace ---
   at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)
   at System.Web.Configuration.CompilationSection.LoadAllAssembliesFromAppDomainBinDirectory()
   at System.Web.Configuration.CompilationSection.LoadAssembly(AssemblyInfo ai)
   at System.Web.Configuration.AssemblyInfo.get_AssemblyInternal()
   at System.Web.Compilation.BuildManager.GetReferencedAssemblies(CompilationSection compConfig)
   at System.Web.Compilation.WebDirectoryBatchCompiler..ctor(VirtualDirectory vdir)
   at System.Web.Compilation.BuildManager.BatchCompileWebDirectoryInternal(VirtualDirectory vdir, Boolean ignoreErrors)
   at System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath)
   at System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile)
   at System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile)
   at System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean noAssert)
   at System.Web.Compilation.BuildManager.GetCompiledType(String virtualPath)
   at System.Web.Script.Services.WebServiceData.GetWebServiceData(HttpContext context, String virtualPath, Boolean failIfNoData, Boolean pageMethods, Boolean inlineScript)
   at System.Web.Script.Services.RestHandler.CreateHandler(HttpContext context)
   at System.Web.Script.Services.ScriptHandlerFactory.GetHandler(HttpContext context, String requestType, String url, String pathTranslated)
   at System.Web.HttpApplication.MaterializeHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Inner exception:
System.IO.FileLoadException: Could not load file or assembly 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' or one of its dependencies. Failed to grant permission to execute. (Exception from HRESULT: 0x80131418) File name: 'itextsharp, Version=4.1.2.0, Culture=neutral, PublicKeyToken=8354ae6d2174ddca' ---> System.Security.Policy.PolicyException: Execution permission cannot be acquired.
   at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Boolean checkExecutionPermission)
   at System.Security.SecurityManager.ResolvePolicy(Evidence evidence, PermissionSet reqdPset, PermissionSet optPset, PermissionSet denyPset, PermissionSet& denied, Int32& securitySpecialFlags, Boolean checkExecutionPermission)
   at System.Reflection.Assembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, Assembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection)
   at System.Reflection.Assembly.InternalLoad(AssemblyName assemblyRef, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.InternalLoad(String assemblyString, Evidence assemblySecurity, StackCrawlMark& stackMark, Boolean forIntrospection)
   at System.Reflection.Assembly.Load(String assemblyString)
   at System.Web.Configuration.CompilationSection.LoadAssemblyHelper(String assemblyName, Boolean starDirective)

web.config第59行为:

<add assembly="*"/>

当这些发生时,这些站点将一直运行,直到我们回收应用程序池。网站可能会在这之前运行几天/几周,或者在一小时内运行两次。我无法将此精确定位到系统中的任何特定请求/功能。

在本例中,它指向itextsharp,但它随机指向应用程序引用的任何程序集,包括内部程序集和外部程序集。

运行caspol将验证dll是否具有完全信任权限:

C:\Windows\Microsoft.NET\Framework64\v2.0.50727>caspol -rsg D:\...\bin\itextsharp.dll
Microsoft (R) .NET Framework CasPol 2.0.50727.3053
Copyright (c) Microsoft Corporation.  All rights reserved.

Level = Enterprise

Code Groups:

1.  All code: FullTrust


Level = Machine

Code Groups:

1.  All code: Nothing
   1.1.  Zone - MyComputer: FullTrust


Level = User

Code Groups:

1.  All code: FullTrust

Success

我们的应用程序运行在三台服务器上,其中两台在服务器2008 Web x64上,而第三台运行服务器2008 R2 Web x64,所有服务器都安装了.NET 3.5,没有安装.NET 4.0。

问题 只发生 在运行2008非R2的前两个上。

在所有三台服务器上运行depends.exe可为非R2服务器提供相同的结果:

• 我的dll显示为x86(编译为anycpu,在x64 w3wp中运行),所有其他模块显示为x64。
• 缺少ieshims.dll和linkinfo.dll-根据谷歌的说法,这两个文件都是过眼云烟。

第三台服务器显示的是相同的,除了它 没有 linkinfo.dll小姐

所有服务器都在已被授予必要权限的自定义域帐户下运行iis7(r2 1为7.5):

aspnet_regiis -ga [user]

加载用户配置文件设置为 假 在所有三台服务器上。我在一台故障服务器上尝试将此设置为true,根据: IIS7 Failed to grant minimum permission requests

通过运行processmonitor,我可以看到它现在正在对各种临时文件使用c:\users\temp\appdata\local\temp目录,而其他文件则没有使用任何这样的目录。到目前为止,我会让它以这种方式运行,看看这是否会改变什么。不过,考虑到第三台服务器没有显示出问题,但仍将“加载用户配置文件”设置为相同的值false,我对此表示怀疑。

我还尝试在所有三台服务器上运行fuslogvw,将绑定失败记录到磁盘。所有三台服务器都报告了vjsharpcodeprovider和cppcodeprovider的相同绑定错误,但这些错误看起来也是正常的,可以通过在生成期间不定义调试和跟踪常量来解决。

我们在每台服务器上运行大约500个网站(相同,负载平衡),其中50个处于中等负载下,无论是在高负载下还是在最小负载下都会出现问题。

现在我正在等待错误再次发生,所以我希望能够看到一个模式,并确定“加载用户配置文件”是否缓解了这个问题。在此期间任何建议都是非常欢迎的!另外,我不明白缺少“加载用户配置文件”会导致这样的问题吗?更进一步说,它在R2上看起来是如何工作的,但在普通的2008上却不是这样?

谢谢!