Asp.Net Core - The configured user limit (128) on the number of inotify instances has been reached

the asp.net core MVC report error after certain times of query to the mysql database (on Ubuntu 14.04/16.04) with the following message: "The configured user limit (128) on the number of inotify instances has been reached." It can be identified that the error was raised because of the controller opened too many files and exceeded the limits of iNotify setting (in the /proc/sys/fs/inotify/max_user_instances). But I was just baffled when the ASP.NET opened files on each http request and why it doesn't close the file properly? Any one encounted this issue too? Remarks: I was using Mysql.data.core and mysql.data.entityframeworkcore provider.

    private static string classiferstring = "sports,outdoor,startup,pets,child,adult,elderly";

    [AllowAnonymous]
    [HttpGet]
    public async Task<object> Classify([FromQuery] string classifyword)
    {
        string[] classifers = classiferstring.Split(',');
        if (!classifers.Contains(classifyword))
        {
            return new
            {
                status = 0,
                info = "WrongClassifier",
                Data = ""
            };
        }

        try
        {
            var predata = await (from d in _context.descriptor
                              join a in _context.combination on d.ID equals a.ID
                              select new ProductsVM
                              {
                                  CREATETIME = a.CREATETIME,
                                  ID = a.ID,
                                  COMPANY = a.COMPANY,
                                  NAME = a.NAME,
                                  PRICE = a.PRICE,
                                  TYPE = a.TYPE,
                                  HEADPHOTO = a.HEADPHOTO,
                                  REMARK = a.REMARK,

                                  Tags = d.Tags,
                                  Classifier = d.Classifier,
                                  OriginName = d.OriginName,
                                  Briefing = d.Briefing
                              }).ToListAsync();
            var data = (from x in predata
                          where x.Classifier.Contains(classifyword.ToLower())
                          select x).ToList();

            if(predata.Count<=0)
            {
                return new
                {
                    status = 2,
                    info = "NoResult",
                    Data = ""
                };
            }else
            {
                return new
                {
                    status = 1,
                    info = "Success",
                    Data = data
                };
            };
        }
        catch(Exception e)
        {
            return new
            {
                status = 0,
                info = "Error",
                Data = e.Message
            };
        }
    }

Please notice the exception was raised only in the try/catch code block instead of immediately after the action is invokded.

Many thanks if anyone has some clue to resolve this problem.

@dmitry-pavlov is wrong, you can use the default builder as the last builder added wins - but doing so makes appsettings.json settings override all other config sources, env and command line. See https://github.com/dotnet/AspNetCore.Docs/pull/22391 where this will soon be officially documented. If you don't care about appsettings.json reloads, set it to false

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureAppConfiguration((hostingContext, config) =>
        {
            config.AddJsonFile("appsettings.json",
                optional: true,
                reloadOnChange: false);
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });
}