Question

在生产中使用带有EF 6应用程序的C＃ASP.NET MVC大约3个月之后，我们注意到对数据库的一次调用花费的时间比以前长得多。它开始的时间不到一秒钟。没有逐渐增加，它跳到15秒。

我已启用了对EF上下文的登录。这是代码。

public async Task<int> SetToProcessing(string[] documentIds, string userName)
{
    if (documentIds.Count() == 0)
        return 0;

    var assigned = 0;
    using (var db = new InvoiceDeliveryContext())
    {
        db.Database.Log = message => logger.Debug("EF6-" + message);
        foreach (var id in ConvertToLong(documentIds))
        {
            if (id == 0)
                continue;
            var doc = db.Documents.Find(id);
            if (doc.Status == DocumentStates.Processing)
            {
                logger.Debug($"Document Id {id} not being set to processed.  Already set to Processing.");
                continue;
            }
            assigned++;
            doc.AssignedTo = userName;
            doc.Status = DocumentStates.Processing;
            doc.History.Add(new History
            {
                Audit = "Set back to Processing.",
                CreatedBy = userName,
                Document = doc,
            });

            logger.Debug($"Assigned Document with ID={id} for Processing to {userName}.");
        }
        try
        {
            await db.SaveChangesAsync();
        }
        catch (Exception e)
        {
            logger.Error(e, "An exception occurred trying to set documents to processing.");
        }
    }
    return assigned;
}

以下是生成的日志。请注意，在打开连接后，会发生约15秒的延迟。

[5] 2017-07-27 06:47:32.4742 EF6-Opened connection at 7/27/2017 6:47:32 AM -05:00  
[5] 2017-07-27 06:47:47.0677 EF6-SELECT TOP (2)   
    [Extent1].[DocumentId] AS [DocumentId],   
    [Extent1].[AssignedTo] AS [AssignedTo],   
    [Extent1].[ApprovedBy] AS [ApprovedBy],   
    [Extent1].[AttachmentId] AS [AttachmentId],   
    [Extent1].[FileLocation] AS [FileLocation],   
    [Extent1].[FileSize] AS [FileSize],   
    [Extent1].[Name] AS [Name],   
    [Extent1].[Pages] AS [Pages],   
    [Extent1].[Part] AS [Part],   
    [Extent1].[Parts] AS [Parts],   
    [Extent1].[IsMerged] AS [IsMerged],   
    [Extent1].[ReceivedOn] AS [ReceivedOn],   
    [Extent1].[Status] AS [Status],   
    FROM [InvoiceDelivery].[Documents] AS [Extent1]  
    WHERE [Extent1].[DocumentId] = @p0   
[5] 2017-07-27 06:47:47.0980 EF6--- p0: '7149' (Type = Int64)  
[5] 2017-07-27 06:47:47.0980 EF6--- Executing at 7/27/2017 6:47:47 AM -05:00  
[5] 2017-07-27 06:47:47.1401 EF6--- Completed in 28 ms with result: SqlDataReader

我已多次捕获上述过程的日志，并且它们都显示大约15秒的延迟。其他查询不会遇到此问题。知道为什么我会看到这种延迟吗？

修改

我无法使用新的控制台应用程序重现延迟 private static async Task GoAsync() { var repo = new InvoiceRepository(); await repo.SetToProcessing(new[] { "7149" }, "JD Montgomery"); }

Answer 1

记录日志。除了几个服务（包括UI层日志）之外，我不会将所有内容记录到同一个数据库表中。使用DEBUG级别，此问题正在发生。一旦我降低级别或停止登录数据库，问题就会消失。

我猜测Log表上有锁。

在EF 6中首次调用数据库之前的15秒延迟

修改

1 个答案: