Multithreading vb.net -- Threads seem to step on each other

  • Thread starter Thread starter Steven Thomas
  • Start date Start date
S

Steven Thomas

I am trying to write a windows service application to create reports.
This program reads from a MSSQL database where the report request are
placed. When it finds a new request a new thread is created and a sub
is called to run the report and save the snp file out of access. If I
slow the code down (with sleep statements) all of the reports run just
fine. How ever if I let it run at normal speed, it will create 2
threads wait for 1 sec and create 2 more (if there are request in the
queue)

My code:
-------------------------------------------------------------------------
Private Sub StartGPReportServer()
Try
'Dim some variables........
While IsRunning
' LOOP THROUGH THE AVAILABLE THREADS
' I HAVE AN ARRAY WITH A RECORD FOR EACH THREAD THE
APPLICATION
' CAN CREATE. IN THIS CASE 6
While c < threads
' CHECK TO SEE IF THERE ARE REPORTS TO BE RUN
If arThreadCnts(3, c) = 0 Then
'POLL THE QUEUE TO LOOK FOR WORK
dtReportToRun = cFunctions.polldb(arQueues(x),
arThreadCnts(0, c))
' IF THERE IS WORK TO BE DONE READ THE DATA
FROM THE REPORTQUEUE
If CInt(dtReportToRun.Rows.Count) > 0 Then
arThreadCnts(3, c) = 1
'CInt(arThreadCnts(3,c)) + 1
'READ THE DATA ABOUT THE REQUEST
Dim othread1 As New Thread(AddressOf
cAccessFunc.CAccessSnapShot)

'Create the new thread
'SET THE PROPERTIES OF THE SUB
othread1.Name = CStr(arThreadCnts(1,
c))
cAccessFunc.pQConnectionString =
arQueues(x)
cAccessFunc.pInputFileName =
CStr(dtReportToRun.Rows(0).Item("InputFileName"))
.........
'Start the thread
othread1.start()
End If
End If
c += 1
End While
c = 0
Thread.CurrentThread.Sleep(1000)
End While
Catch errorVariable As Exception
'Error trapping
cFunctions.WriteEventLog("GPReport Could not start : " &
CStr(System.DateTime.Now()) & " " & errorVariable.Message.ToString)
End Try
End Sub
----------------------------------------------------------

What happens is that I get a set of reports running, but only one ever
seems to finsih. I have put code in to write to the even log at
different points in the process. If a report is picked up, and never
finishes processing, it seems after looking at the event log that and
it never makes it inside of the sub.

Am I stepping on my on threads? if so can someone point me in the
right direction?

Thanks
 
Were exactly to instantiate cAccessFunc? Just guessing here but it appears
that you never instantiate new version of this class and that would be
consistent with the behvior you are experiencing.
 
I moved the dim cAccessFunc as new....
line down to where the threads are created and it fixed the problem

Thanks for your help
 
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