Solved

VB.NET Datatable "Index was out of range."

Posted on 2010-11-19
2
747 Views
Last Modified: 2012-05-10
I have VB.NET App with 2 threads.

Both threads read and update a Datatable.

When the App starts the structure and rows (20c, 100 r) are setup.

The Datatable is basically an object to hold information used by the program, the threads read/change this data while it runs.

THE PROBLEM:

Randomly get the error: "Index was out of range. Must be non-negative and less than the size of the collection."

When the code breaks on this error I can confirm using the "Immediate Window" that the reference is valid.

A typical reference is: dtData(10)("Name")

The Datatable schema, # rows, and # cols are not changing and I'm sure the Index is valid, and the ref Col exists.

Is there some other problem with 2 threads accessing the same Datatable??

Thanks!
0
Comment
Question by:cgraham2
2 Comments
 
LVL 4

Accepted Solution

by:
Andre412 earned 500 total points
ID: 34176074
Are you balancing thread access ?

when using multi threaded datatable access you must balance access to the table.

lookup using the synclock

An example of how i use it on a dataset
declare this class wide
 
Private oSyncLockTables As New Object

Open in new window


then in functions that access the table
 If Monitor.TryEnter(oSyncLockTables, 500) Then
            Try
                If priDataSet.Tables.IndexOf(tblName.ToString) > -1 Then
                    Rtn = True
                Else
                    ''delete any reference to this table in the maintenance table (if there is one)
                    'TableIndex_DeleteRow(tblName.ToString)
                    Rtn = False
                End If
            Finally : Monitor.Exit(oSyncLockTables) : End Try
        End If

Open in new window

0
 
LVL 83

Expert Comment

by:CodeCruiser
ID: 34179694
Does the program need to show the datatable while it is being processed? If not, use separate datatables for both threads and merge them into one at the end.
0

Featured Post

Free Tool: Postgres Monitoring System

A PHP and Perl based system to collect and display usage statistics from PostgreSQL databases.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Complex SQL statement in VB.NET 7 31
ASP.NET (VB) return a record 2 35
SSIS Start 2 20
VB.net Adding a row to a DataGridView that has a checkbox column 5 22
For those of you who don't follow the news, or just happen to live under rocks, Microsoft Research released a beta SDK (http://www.microsoft.com/en-us/download/details.aspx?id=27876) for the Xbox 360 Kinect. If you don't know what a Kinect is (http:…
More often than not, we developers are confronted with a need: a need to make some kind of magic happen via code. Whether it is for a client, for the boss, or for our own personal projects, the need must be satisfied. Most of the time, the Framework…
This video shows how to quickly and easily add an email signature for all users on Exchange 2016. The resulting signature is applied on a server level by Exchange Online. The email signature template has been downloaded from: www.mail-signatures…
A short tutorial showing how to set up an email signature in Outlook on the Web (previously known as OWA). For free email signatures designs, visit https://www.mail-signatures.com/articles/signature-templates/?sts=6651 If you want to manage em…

790 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question