Asp.Net application randomly locks up with multiple users

Question

Technology - Asp.Net 4.5, SqlServer 2012

I have a (Master Page Web Application) that seems to randomly lock up on functions that do sql queries, inserts, or updates. The queries are used to populate GridView's, ListView's, DataTable's for whatever page happens to be requested or postback.

If only one user is on then there is no lockups or errors. If multiple users are on than it randomly locks up with error. The error stacktrace points to functions with database interaction. The last line of stacktrace is "ProcessRequestMain". I can't seem to figure this one out yet. Has anyone else ran across this issue?

Error Message Details:

Object reference not set to an instance of an object.

Error StackTrace:

at MudderTrucks.Items.LoadItems()
at MudderTrucks.Items.Page_Load(Oject.sender, EventArgs e)
at System.Web.UI.Control.OnLoad(EventArgs e)
at System.Web.UI.Control.LoadRecursive()
at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

You haven't provided nearly enough information to diagnose the issue. Need to see the relevant code. — EkoostikMartin, May 15 '14 at 20:21
The Waiting wheel (modalpopupextender) will grind for several minutes, then the user is taken to the CustomError page. — Troy Mitchel, May 15 '14 at 20:30
What is the exception that's being thrown? This is pretty important to be able to give reasoned answers. — hatchet - done with SOverflow, May 15 '14 at 20:31
But it happens randomly. I did a test with some users, and if we made simultaneous requests than the issue happened, otherwise everything seemed to work fine. — Troy Mitchel, May 15 '14 at 20:32
@hatchet I've edited the post to show one of the errors. I am also using update panels. not sure if that is a concern. — Troy Mitchel, May 15 '14 at 20:46
If its a "database"-problem, you can try adding this to the connectionstring: MultipleActiveResultSets=True — Daniel Björk, May 15 '14 at 20:47

score 0 · Answer 1 · answered May 15 '14 at 20:24

0

I would check if you have uncommitted transactions as that can cause table locks. Also make sure db connections are being closed.

answered May 15 '14 at 20:24

TGH

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You may be right. It sure seems like a transactional issue. I'll check on that. – Troy Mitchel May 15 '14 at 20:35

Troy Mitchel · Accepted Answer · 2014-05-21T13:44:31.190

The issue: Connection variable in a module. I overlooked this.

Dim MyConnection As New SqlClient.SqlConnection( _
        ConfigurationManager.ConnectionStrings("MyConnection").ConnectionString)

Answer: Remove the module level variable and add it as a parameter to your function

Public Function GetData2(ByVal Sql As String, _
         MyConnection As SqlClient.SqlConnection) As DataTable

    '...code...'

End Function

Note: As a better alternative to using public functions in a module, I've created a PageBase class and inherited it on the pages requiring the functions. I added the connection variable at the top of class as it will expose it only to the page inheriting it. Or... you can create the connection in the page code behind and pass it to the function.

Page Code Behind

Public Class MyPage
    Inherits PageBase

End Class

PageBase Class

Public Class PageBase
    Inherits System.Web.UI.Page

    Public MyConnection As New SqlClient.SqlConnection( _
        ConfigurationManager.ConnectionStrings("MyConnection").ConnectionString)

    Public Function GetData2(ByVal Sql As String) As DataTable

        '...code...'

    End Function

End Class

Conclusion: I tried both of these methods and they fixed the posted issue.

Asp.Net application randomly locks up with multiple users

2 Answers2