由於內存壓力，Sql Server 2008 R2：AppDomain被標記爲卸載

Question

我正在運行帶有服務使用的數據庫的Sql Server 2008 R2 Express。數據庫在服務啓動時通過AttachDBFileName選項附加。該服務不斷運行並且僅在自動更新後重新啓動。

有時候，這種模式出現在SQL Server日誌：

10/09/2013 11:18:05,spid18s,Unknown,AppDomain 6 (..MDF.dbo[runtime].5) unloaded. 
10/09/2013 11:18:05,spid1s,Unknown,AppDomain 6 (...MDF.dbo[runtime].5) is marked for unload due to memory pressure. 
10/09/2013 11:16:16,spid53,Unknown,AppDomain 6 (....MDF.dbo[runtime].5) created. 
10/09/2013 11:16:00,spid28s,Unknown,AppDomain 5 (....MDF.dbo[runtime].4) unloaded. 
10/09/2013 11:16:00,spid1s,Unknown,AppDomain 5 (....MDF.dbo[runtime].4) is marked for unload due to memory pressure. 
10/09/2013 11:15:41,spid53,Unknown,AppDomain 5 (...MDF.dbo[runtime].4) created. 
10/09/2013 11:14:20,spid24s,Unknown,AppDomain 4 (...MDF.dbo[runtime].3) unloaded. 
10/09/2013 11:14:20,spid1s,Unknown,AppDomain 4 (...MDF.dbo[runtime].3) is marked for unload due to memory pressure. 

這會導致性能問題，因爲每次在AppDomain重新啓動時，緩衝區被丟棄，數據庫沒有響應幾秒鐘。

根據http://support.microsoft.com/kb/917271?wa=wsignin1.0，這可能是由於內存泄漏或CLR模塊中的其他錯誤（即使我認爲應該在Sql Server 2008 R2中修復）。有安裝了一個CLR模塊，用以下代碼：

[Serializable] 
[Microsoft.SqlServer.Server.SqlUserDefinedAggregate(Format.UserDefined, 
    MaxByteSize=8000)] 
public class Concatenate : IBinarySerialize 
{ 
    /// <summary> 
    /// The variable that holds the intermediate result of the concatenation 
    /// </summary> 
    private StringBuilder intermediateResult; 

    public void Init() 
    { 
     // Put your code here 
     intermediateResult = new StringBuilder(); 
    } 

    public void Accumulate(SqlString Value) 
    { 
     if (Value.IsNull) 
      return; 

     intermediateResult.Append(Value.Value).Append(", "); 
    } 

    public void Merge(Concatenate Group) 
    { 
     intermediateResult.Append(Group.intermediateResult); 
    } 

    public SqlString Terminate() 
    { 
     string output = string.Empty; 
     //delete the trailing comma, if any 
     if (intermediateResult != null && intermediateResult.Length > 0) 
      output = intermediateResult.ToString(0, intermediateResult.Length - 2); 

     return new SqlString(output); 
    } 

    #region IBinarySerialize Members 

    public void Read(System.IO.BinaryReader r) 
    { 
     if (r == null) throw new ArgumentNullException("r"); 
     intermediateResult = new StringBuilder(r.ReadString()); 
    } 

    public void Write(System.IO.BinaryWriter w) 
    { 
     if (w == null) throw new ArgumentNullException("w"); 
     w.Write(intermediateResult.ToString()); 
    } 

    #endregion 
} 

此外，MS交換在服務器上運行，使用的對MDB商店自由存儲器高達90％。然而，我發現過去在其他帶有大量空閒內存的服務器上出現這樣的錯誤，所以我認爲內存壓力並不是問題的真正原因。

任何想法可能會導致此問題？

Answer 1

看看這裏，看看是否有同樣的問題：https://teusje.wordpress.com/2015/05/07/slow-performance-on-asp-net-mvc-application-using-entityframework-sql-server/