LINQ DataContext causes trouble

Question

I have a global datacontext that I renew each request:

    protected void Page_Load(object sender, EventArgs e)
    {

        Response.ContentType = "application/json";
        Response.Write(GetResponse());
        Response.End();
    }


    public string GetResponse()
    {
        string fileName = this.Page.Request.PathInfo;
        fileName = fileName.Remove(0, fileName.LastIndexOf("/") + 1);

        DataContext.Renew();
        MethodInfo method = this.GetType().GetMethod(fileName);
        if (method == null)
            throw new InvalidOperationException(
                string.Format("Unknown method {0}.", fileName));
        return (string)method.Invoke(this, new object[0]);
    }

But for whatever reason, often when I get multiple requests (Like multiple ajax calls,) I get errors like these:

   at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Data.Linq.DataContext.GetTable(MetaTable metaTable)
   at System.Data.Linq.DataContext.GetTable[TEntity]()
   at LibKezberProjectManager.KezberPMDBDataContext.get_Cases() in c:\Users\jlarouche\Documents\Visual Studio 2012\Projects\KezberProjectManager\LibKezberProjectManager\KezberPMDB.designer.cs:line 204
   at LibKezberProjectManager.Data.Cases.GetAllScheduled() in c:\Users\jlarouche\Documents\Visual Studio 2012\Projects\KezberProjectManager\LibKezberProjectManager\Data.cs:line 113
   at LibKezberProjectManager.Logic.ScheduleManager.GetScheduledCases() in c:\Users\jlarouche\Documents\Visual Studio 2012\Projects\KezberProjectManager\LibKezberProjectManager\Logic.cs:line 1035
   at KezberProjectManager.CalendarServices.GetDates() in c:\Users\jlarouche\Documents\Visual Studio 2012\Projects\KezberProjectManager\KezberProjectManager\CalendarServices.aspx.cs:line 628

I renew the context each request though and it is only used for that request. Am I doing something wrong?

DataContext.Renew() calls db = new KezDBContext();

And all calls use this.

Could the fact that all my accessor methods are static be a problem? I wouldn't think so.

Thanks

FYI: [Should data contexts be static](http://stackoverflow.com/q/4081071/102112) and [Linq to SQL DataContext Lifetime Management](http://www.west-wind.com/weblog/posts/2008/Feb/05/Linq-to-SQL-DataContext-Lifetime-Management) — Oleks, Mar 13 '13 at 20:39

score 3 · Accepted Answer · answered Mar 13 '13 at 19:30

You're not providing the code for your DataContext, but I assume it is declared as a static field/property. This is very much a problem, in that the DataContext is not thread-safe, but each concurrent request in ASP.NET is served on a separate thread. You need to create a DataContext per request. This can be achieved in many ways, the simplest (but not necessarily the most maintainable) is probably to associate the DataContext with the Page object by creating a base class derived from System.Web.UI.Page from which all your pages are in turn derived.

LINQ DataContext causes trouble

1 Answers1