Bdtjtk

I have a web application written using ASP.NET MVC (C#), Entity Framework and an Oracle database. In one of the controllers I have code similar to the following (stripped down to show only what I consider necesary for this question):

    using (var context = CreateContext())

    {

        //Other code ...

        var workItem = //Get work item from context



        var nextReviewers =

            await context.WorkItemReviewers

                         .Where(r => r.WorkItemId == workItem.Id)

                         .Where(r => r.Position > workItem.NextReviewerPosition)

                         .OrderBy(r => r.Position)

                         .ToArrayAsync();

        if (nextReviewers.Count() > 0)

        {

            workItem.Status = "A";

            workItem.StatusDetails = "A";

            workItem.NextReviewerPosition = nextReviewers.First().Position;



            //Other Code

        }

        else

        {

            workItem.Status = "B";

            workItem.StatusDetails = "B";

            workItem.NextReviewerPosition = null;

        }



        //Other Code



        await context.SaveChangesAsync();

    }

Based on the code above, I never expect the values of Status or StatusDetails to ever be different but I have a situation in production where two requests came in about 3-4 milliseconds apart and now, inexplicably, I have the following values in the database: Status = "B"; StatusDetails = "A".

Am I missing something? Is there a logical explanation for this based on how EntityFramework (against Oracle 11g) might behave in ASP.NET?

Based on the code above, given that the workItem entity updated was loaded within the scope of the DB context and that the 2 values are strings, I'd have to say with 99.5% certainty that this code is not responsible for the behaviour you are seeing. (though I will definitely be watching this item to see if that is proven wrong:) I would be taking a close look at everywhere that either Status or StatusDetails is being used in relation to the calls made to the service. I suspect some other code is unexpectedly changing one or the other and calling SaveChanges.

A small optimization I can suggest:

var nextReviewer = context.WorkItemReviewers

    .Where(r => r.WorkItemId == workItem.Id

        && r.Position > workItem.NextReviewerPosition)

    .OrderBy(r => r.Position)

    .Select(r => new { r.Position }) // Add any other details you may need from reviewer and other related entities.

    .FirstOrDefault();



if (nextReviewer != null)

{

    workItem.Status = "A";

    workItem.StatusDetails = "A";

    workItem.NextReviewerPosition = nextReviewer.Position;

    //Other Code

}

else

{

    workItem.Status = "B";

    workItem.StatusDetails = "B";

    workItem.NextReviewerPosition = null;

}

By using .Select() you can optimize the query to just return back the columns from the tables you need which will make calls to the DB faster. Unless the query is expected to be relatively heavy in terms of time (> ~500ms for instance) I'd also avoid the async operation. It's purpose is to make the server more responsive when dealing with bigger operations. Using it on everything will make all operations a wee bit slower than necessary. Once you've optimized the data coming back, then async can be considered if it still requires a bit of time to chew through.