解決網頁回應『Server is too busy』

WEB Server版本：IIS6
ASP.NET應用程式目錄：AAA_WEB
使用者近日常回報網頁偶而會出現『Server is too busy』的錯誤訊息。

 

原因

我們在使用者反應該問題時，將 ASP.NET Worker Process : aspnet_wp進行Dump，Dump 工具為DebudDialog ，並將dump檔交由微軟工程師進行解析，微軟回覆以下結果：

1. 發生問題期間，由於ASP.NET bin目錄及config檔有異動，因此Ａpplication domain不斷地被shutdown。以下是解析片段：
   
   0:020> !DumpHttpRuntime
   Going to dump the HttpRuntimes found in the heap.
   HttpRuntime 0x1c6b41dc:
   _shutDownStack:    at System.Environment.GetStackTrace(Exception e, Boolean needFileInfo)
      at System.Environment.get_StackTrace()
      at System.Web.HttpRuntime.ShutdownAppDomain()
      at System.Web.HttpRuntime.OnCriticalDirectoryChange(Object sender, FileChangeEvent e)
      at System.Web.FileChangesMonitor.OnCriticaldirChange(Object sender, FileChangeEvent e)
      at System.Web.DirectoryMonitor.FireNotifications()
      at System.Web.Util.WorkItem.CallCallbackWithAssert(WorkItemCallback callback)
      at System.Web.Util.WorkItem.OnQueueUserWorkItemCompletion(Object state)
      at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
      at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)
   _shutDownMessage: Change Notification for critical directories.
   bin dir change or directory rename
   Change Notification for critical directories.
   bin dir change or directory rename
   Change Notification for critical directories.
   _shutdownInProgress: 1
   _requestQueue:
   0x186b8dd0
   _appDomainAppPath: C:\Inetpub\wwwroot\AAA_WEB\
   _appDomainAppId: /LM/W3SVC/1/ROOT
   _fcm:
   HttpRuntime 0x1c600544:
   _shutDownStack:    at System.Environment.GetStackTrace(Exception e, Boolean needFileInfo)
      at System.Environment.get_StackTrace()
      at System.Web.HttpRuntime.ShutdownAppDomain()
      at System.Web.Hosting.HostingEnvironment.ShutdownThisAppDomainOnce()
      at System.Web.Hosting.HostingEnvironment.InitiateShutdownWorkItemCallback(Object state)
      at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
      at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)
   _shutDownMessage: CONFIG change
   HostingEnvironment caused shutdown
   _shutdownInProgress: 1
   _requestQueue:
   0x185c2790
   _appDomainAppPath: C:\Inetpub\wwwroot\Public\
   _appDomainAppId: /LM/W3SVC/1/Root/Public
   _fcm:
   HttpRuntime 0x18563698:
   _shutDownStack:    at System.Environment.GetStackTrace(Exception e, Boolean needFileInfo)
      at System.Environment.get_StackTrace()
      at System.Web.HttpRuntime.ShutdownAppDomain()
      at System.Web.HttpRuntime.OnCriticalDirectoryChange(Object sender, FileChangeEvent e)
      at System.Web.FileChangesMonitor.OnCriticaldirChange(Object sender, FileChangeEvent e)
      at System.Web.DirectoryMonitor.FireNotifications()
      at System.Web.Util.WorkItem.CallCallbackWithAssert(WorkItemCallback callback)
      at System.Web.Util.WorkItem.OnQueueUserWorkItemCompletion(Object state)
      at System.Threading._ThreadPoolWaitCallback.WaitCallback_Context(Object state)
      at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
      at System.Threading._ThreadPoolWaitCallback.PerformWaitCallback(Object state)
   _shutDownMessage: Change Notification for critical directories.
   bin dir change or directory rename
   Change Notification for critical directories.
   bin dir change or directory rename
   bin dir change or directory rename
   …
   Change in C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3c653636\bc2125b3\hash.web
   Change in C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3c653636\bc2125b3\hash.web
   Change in C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\3c653636\bc2125b3\hash.web
   _shutdownInProgress: 1
   _requestQueue:
   0x14564120
   _appDomainAppPath: C:\Inetpub\wwwroot\AAA_WEB\
   _appDomainAppId: /LM/W3SVC/1/ROOT
   _fcm:
2. 同時也發現有多達1596次的AppDomainUnloadedException，原因同#1。
   Number of exceptions of this type:     1596
   Exception MethodTable: 7915cc88
   Exception object: 1ca9a59c
   Exception type: System.AppDomainUnloadedException
   Message: Attempted to access an unloaded AppDomain.
   InnerException: <none>
   StackTrace (generated):
   <none>
   StackTraceString: <none>
   HResult: 80131014
3. 下列應用程式的debug沒有設定為false。
   0:020> !finddebugtrue
   Debug set to true for Runtime: 18563698, AppDomain: C:\Inetpub\wwwroot\AAA_WEB\
   Debug set to true for Runtime: 1c600544, AppDomain: C:\Inetpub\wwwroot\Public\
   Debug set to true for Runtime: 1c6b41dc, AppDomain: C:\Inetpub\wwwroot\AAA_WEB\
   Total 4 HttpRuntime objects
4. Web 主機的.NET framework 2.0為RTM版本。
   0:020> !eeversion
   2.0.50727.42 retail
   

解決方法︰

請依下列作法解決此問題：

1. 檢查Ｗeb Server的防毒軟體、檔案監控軟體等，將ASP.NET bin目錄、Temporary ASP.NET Files等目錄加入不要被掃描的清單中，避免相關目錄或config檔案被修改導致application domain shut down，因為下列原因都會導致此問題：
   • Machine.Config, Web.Config or Global.asax 被修改
   • bin 目錄 or 其內容 被修改
   • aspx, ascx or asax重新編譯的次數超過 machine.config or web.config裡ompilation numRecompilesBeforeAppRestart=/> 的設定  (預設值是 15)
   • 應用程式虛擬目錄所指向之實體路徑被修改
   • CAS policy 被修改
   •  web service 被重新啟動
   •  Application(僅限2.0) 的子目錄被刪除
   參考:
   PRB: Session variables are lost intermittently in ASP.NET applications
   http://support.microsoft.com/kb/316148/en-us
   This problem can occur when antivirus software scans the Web application files. During the scanning process, the antivirus software may mark the Global.asax, the Web.config, and/or the Machine.config files as modified. This modification prompts the Microsoft .NET Framework restart the Web application. If the session data is stored in-process, all session data is lost whenever a Web application is restarted.
2. 將下列ASP.NET debug設定false：
   C:\Inetpub\wwwroot\AAA_WEB\
   C:\Inetpub\wwwroot\Public\
   C:\Inetpub\wwwroot\AAA_WEB\
3. 請將所有IIS 6的.NET framework 2.0升級至SP2:
   http://www.microsoft.com/downloads/zh-tw/details.aspx?FamilyID=5B2C0358-915B-4EB5-9B1D-10E506DA9D0F