使用System.DirectoryServices时尝试访问已卸载的appdomain

Question

我们已经实现了一个对Active Directory进行身份验证的成员资格提供程序,它使用的是System.DirectoryServices.在带有webdev服务器的Visual Studio 2010上的ASP.Net MVC 3应用程序中使用此成员资格提供程序时,我们有时(6次中有1次)在登录应用程序时会出现异常.

System.IO.FileNotFoundException: Could not load file or assembly 'System.Web' or one of its dependencies. The system cannot find the file specified.
File name: 'System.Web' 
at System.Reflection.RuntimeAssembly._nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.nLoad(AssemblyName fileName, String codeBase, Evidence assemblySecurity, RuntimeAssembly locationHint, StackCrawlMark& stackMark, Boolean throwOnFileNotFound, Boolean forIntrospection, Boolean suppressSecurityChecks)
at System.Reflection.RuntimeAssembly.LoadWithPartialNameInternal(AssemblyName an, Evidence securityEvidence, StackCrawlMark& stackMark)
at System.DirectoryServices.AccountManagement.UnsafeNativeMethods.IADsPathname.Retrieve(Int32 lnFormatType)
at System.DirectoryServices.AccountManagement.ADStoreCtx.LoadDomainInfo()
at System.DirectoryServices.AccountManagement.ADStoreCtx.get_DnsDomainName()
at System.DirectoryServices.AccountManagement.ADStoreCtx.GetGroupsMemberOfAZ(Principal p)
at System.DirectoryServices.AccountManagement.UserPrincipal.GetAuthorizationGroupsHelper()
at System.DirectoryServices.AccountManagement.UserPrincipal.GetAuthorizationGroups()

=== Pre-bind state information ===
LOG: DisplayName = System.Web (Partial)
WRN: Partial binding information was supplied for an assembly:
WRN: Assembly Name: System.Web | Domain ID: 2
WRN: A partial bind occurs when only part of the assembly display name is provided.
WRN: This might result in the binder loading an incorrect assembly.
WRN: It is recommended to provide a fully specified textual identity for the assembly,
WRN: that consists of the simple name, version, culture, and public key token.
WRN: See whitepaper http://go.microsoft.com/fwlink/?LinkId=109270 for more information and common solutions to this issue.
Calling assembly : HibernatingRhinos.Profiler.Appender, Version=1.0.0.0, Culture=neutral, PublicKeyToken=0774796e73ebf640.

调用程序集是HibernatingRhinos.Profiler.Appender所以在log4net配置中禁用了探查器后我们得到了真正的异常:

System.AppDomainUnloadedException: Attempted to access an unloaded appdomain. (Except   at System.StubHelpers.StubHelpers.InternalGetCOMHRExceptionObject(Int32 hr, IntPtr pCPCMD, Object pThis)
at System.StubHelpers.StubHelpers.GetCOMHRExceptionObject(Int32 hr, IntPtr pCPCMD, Object pThis)
at System.DirectoryServices.AccountManagement.UnsafeNativeMethods.IADsPathname.Retrieve(Int32 lnFormatType)
at System.DirectoryServices.AccountManagement.ADStoreCtx.LoadDomainInfo()
at System.DirectoryServices.AccountManagement.ADStoreCtx.get_DnsDomainName()
at System.DirectoryServices.AccountManagement.ADStoreCtx.GetGroupsMemberOfAZ(Principal p)
at System.DirectoryServices.AccountManagement.UserPrincipal.GetAuthorizationGroupsHelper()
at System.DirectoryServices.AccountManagement.UserPrincipal.GetAuthorizationGroups()

异常总是以相同的方法抛出,但是现在我们无法重现它,因为它是随机发生的,但大约是6次中的1次.但是,在使用II而不是内置的Visual Studio 2010 Web服务器时,我们不会遇到异常.

在Visual Studio webdev的上下文中使用多个appdomains时,它可能与竞速条件有关,但这只是猜测.我们真的想知道问题的原因是什么,因为我们不希望在生产环境中出现这些异常.

我们发现了2个相似的案例,但没有人找到真正的解决方案:

http://our.umbraco.org/forum/developers/extending-umbraco/19581-Problem-with-custom-membership-and-role-provider

http://forums.asp.net/t/1556949.aspx/1

更新18-05-2011

用于重现异常的最小代码量(在asp.net mvc中),其中userName是您的Active Directory登录名.

using System.DirectoryServices.AccountManagement;
using System.Web.Mvc;

namespace ADBug.Controllers
{
    public class HomeController : Controller
    {
        public ActionResult Index()
        {
            string userName = "nickvane";
            var principalContext = new PrincipalContext(ContextType.Domain);

            UserPrincipal userPrincipal = UserPrincipal.FindByIdentity(
                principalContext,
                IdentityType.SamAccountName,
                userName);

            if (userPrincipal != null)
            {
                PrincipalSearchResult<Principal> list = userPrincipal.GetAuthorizationGroups();
            }

            return View();
        }
    }
}

唉,异常仍然是随机发生的,所以没有完全可重现的bug.

Answer 1

这对我有用(.Net 4):

而不是这个:

principalContext = new PrincipalContext(ContextType.Domain)

使用域字符串创建主要上下文:

例如

principalContext = new PrincipalContext(ContextType.Domain,"MYDOMAIN")

它应该在4.5中修复.请参阅注释,尚未修复,但添加第二个参数仍可用作解决方法.