Question

我正在使用服务使用的数据库运行Sql Server 2008 R2 Express。在服务启动时通过AttachDBFileName选项附加数据库。该服务不断运行，仅在自动更新后重新启动。

有时，此模式显示在Sql Server日志中：

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.

这会导致性能问题，因为每次重新启动AppDomain时，都会删除缓冲区，并且数据库会在几秒钟内无响应。

根据http://support.microsoft.com/kb/917271?wa=wsignin1.0，可能是由于CLR模块中的内存泄漏或其他错误（尽管我认为应该在Sql Server 2008 R2中修复）。安装了一个CLR模块，代码如下：

[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 Exchange正在服务器上运行，使用90％的可用内存用于MDB存储。但是我在过去的其他服务器上看到了这些错误，有大量的可用内存，所以我认为内存压力不是问题的真正原因。

任何可能导致此问题的想法？

Answer 1

如果您遇到同样的问题，请查看此处并阅读：https://teusje.wordpress.com/2015/05/07/slow-performance-on-asp-net-mvc-application-using-entityframework-sql-server/

Sql Server 2008 R2：由于内存压力，AppDomain被标记为卸载

1 个答案: