EF Core5.0 Slow queries

[hwl962589950]

Include your code

In the asynchronous method ToListAsync, when the field VCHAR is too long, the query is slow. When the asynchronization is eliminated and the ToList method is used, the query field is base64 of image transcoding, but I use the log to check, the database query part only takes 2ms. The actual mapping asynchronization is about 20S, and the non-asynchronization requires about 2S

Code

            Stopwatch stopwatch = new Stopwatch();
            Console.WriteLine($"ToList Time Start");
            stopwatch.Start();
            var test1 = dbContext.CourseTree.ToList();
            stopwatch.Stop();
	    Console.WriteLine($"ToList Time {stopwatch.ElapsedMilliseconds}ms End");

            Console.WriteLine($"ToListAsync Time Start");
            stopwatch.Restart();
            var test2 = await dbContext.CourseTree.ToListAsync();
            stopwatch.Stop();
            Console.WriteLine($"ToListAsync Time {stopwatch.ElapsedMilliseconds}ms End");

Log

ToList Time Start
info: 2021-02-19 11:19:35.263 RelationalEventId.CommandExecuted[20101] (Microsoft.EntityFrameworkCore.Database.Command)
      Executed DbCommand (3ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT [c].[Id], [c].[CourseId], [c].[CourseTreeMainBoby], [c].[CourseTreeMainType], [c].[CreationTime], [c].[Name], [c].[OrderByIndex], [c].[ParentId], [c].[TreePath]
      FROM [CourseTree] AS [c]
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (3ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT [c].[Id], [c].[CourseId], [c].[CourseTreeMainBoby], [c].[CourseTreeMainType], [c].[CreationTime], [c].[Name], [c].[OrderByIndex], [c].[ParentId], [c].[TreePath]
      FROM [CourseTree] AS [c]
ToList Time 93ms End
ToListAsync Time Start
info: 2021-02-19 11:19:35.353 RelationalEventId.CommandExecuted[20101] (Microsoft.EntityFrameworkCore.Database.Command)
      Executed DbCommand (0ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT [c].[Id], [c].[CourseId], [c].[CourseTreeMainBoby], [c].[CourseTreeMainType], [c].[CreationTime], [c].[Name], [c].[OrderByIndex], [c].[ParentId], [c].[TreePath]
      FROM [CourseTree] AS [c]
info: Microsoft.EntityFrameworkCore.Database.Command[20101]
      Executed DbCommand (0ms) [Parameters=[], CommandType='Text', CommandTimeout='30']
      SELECT [c].[Id], [c].[CourseId], [c].[CourseTreeMainBoby], [c].[CourseTreeMainType], [c].[CreationTime], [c].[Name], [c].[OrderByIndex], [c].[ParentId], [c].[TreePath]
      FROM [CourseTree] AS [c]
ToListAsync Time 26799ms End

EF Core version:
Database provider: (e.g. Microsoft.EntityFrameworkCore.SqlServer)
Target framework: (e.g. .NET 5.0)
Operating system:
IDE: (e.g. Visual Studio 2019 16.3)

[anranruye]

See #23900. For this scenario, don't use Async methods.

[hwl962589950]

See #23900. For this scenario, don't use Async methods.

OK, it's greater than 1MB

[hwl962589950]

OK, it's greater than 1MB

…

------------------&nbsp;原始邮件&nbsp;------------------ 发件人: "anranruye"<[email protected]&gt;; 发送时间: 2021年2月19日(星期五) 中午1:45 收件人: "dotnet/efcore"<[email protected]&gt;; 抄送: " "<[email protected]&gt;; "Author"<[email protected]&gt;; 主题: Re: [dotnet/efcore] EF Core5.0 Slow queries (#24194) See #23900. For this scenario, don't use Async methods. — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub, or unsubscribe.

[roji]

Duplicate of dotnet/SqlClient#593

[roji]

This is unfortunately a SqlClient issue that is out of EF 's control... You can indeed use the sync API as a workaround until that's fixed.

[hwl962589950]

This is unfortunately a SqlClient issue that is out of EF 's control... You can indeed use the sync API as a workaround until that's fixed.

All right. Got the question