How can I be alerted if my recursion decides to start skipping loops? - vb.net

Question

I have a nested For / Next recursion at the heart of a web app I am trying to develop. When I programmed it, I verified its output on an example that nested 3-5 levels and thought all was well.
Lately, I decided to verify an entry in the result set that was nested 12 to 15 levels deep. The resulting percentage was incorrect because some progeny were not recursed.
Because my result set can take so long to run (8-13 hours for the more indepth queries) and I could run the same test on a subset (~150,000 records) of the records in the full database table (~1,200,000 records), I trialled it against the smaller table.
Low and behold it appears to work perfectly. A search that was returning ~56,000 records, returned ~126,000 records (meaning it was previously skipping out a lot of recursions). I verified random sample results to be correct.
Comparing result sets from the same query done on the two database tables, it seems that the missed recursions start to show up with some (not all) of the records that are nested beyond 12 levels deep.
The troubling thing for me is that I need to know when my result set is suspect without having to search the result set for dropped nesting.
Here is the code for the recursive sub:
' lookup table for up to 63 generations '
Dim percentage() As Double = {100, 50, 25, 12.5, 6.25, 3.125, ect. . .}
' DataTable to display results of looping through the db '
Dim t As DataTable
Dim c As DataColumn
Dim r As DataRow
' columns are: id, name, dad, mom, gender, year born, trait, percentage '
Private Sub GetPct(ByRef progeny As List(Of Int32), ByRef gender As List(Of String), ByVal generations As Int16, ByVal count As Int16)
Dim nxtGeneration As Int16 = generations + 1
Dim nxtPercentage As Double = percentage(nxtGeneration)
For i As Int16 = 0 To count
Dim dbConn As New SqlConnection(connString)
Dim j As Int16 = -1
Dim prog As New List(Of Int32)
Dim gndr As New List(Of String)
If gender(i) = "M" Then
Dim dreader As SqlDataReader
Dim dgetComm As New SqlCommand("d_get", dbConn)
dgetComm.CommandType = CommandType.StoredProcedure
dgetComm.Parameters.Add("#id", SqlDbType.Int)
dgetComm.Parameters("#id").Value = prog(i)
Using dbConn
Try
dbConn.Open()
dreader = dgetComm.ExecuteReader()
If dreader.HasRows = True Then
While dreader.Read()
j += 1
Dim updated As DataRow = t.Rows.Find(dreader(0))
If updated Is Nothing Then
t.BeginLoadData()
r = t.NewRow()
r(0) = dreader(0)
r(1) = dreader(1)
r(2) = dreader(2)
r(3) = dreader(3)
r(4) = dreader(4)
r(5) = dreader(5)
r(6) = dreader(6)
r(7) = nxtPercentage
t.Rows.Add(r)
t.EndLoadData()
prg.Add(dreader(0))
gnd.Add(dreader(4))
Else
prg.Add(dreader(0))
gnd.Add(dreader(4))
updated(7) += nxtPercentage
End If
End While
End If
dgetComm.Dispose()
dgetComm = Nothing
dreader.Close()
dreader = Nothing
Catch ex As Exception
' modify when going live '
lblDetails.Text &= "Error loading to table with get of dam" & Err.Description
End Try
End Using
GetPct(prg, gnd, nxtG, j)
Else
Dim sreader As SqlDataReader
Dim sgetComm As New SqlCommand("s_get", dbConn)
sgetComm.CommandType = CommandType.StoredProcedure
sgetComm.Parameters.Add("#id", SqlDbType.Int)
sgetComm.Parameters("#id").Value = prog(i)
Using dbConn
Try
dbConn.Open()
sreader = sgetComm.ExecuteReader()
If sreader.HasRows = True Then
While sreader.Read()
j += 1
Dim updated As DataRow = t.Rows.Find(srdr(0))
If updated Is Nothing Then
t.BeginLoadData()
r = t.NewRow()
r(0) = sreader(0)
r(1) = sreader(1)
r(2) = sreader(2)
r(3) = sreader(3)
r(4) = sreader(4)
r(5) = sreader(5)
r(6) = sreader(6)
r(7) = nxtPercentage
t.Rows.Add(r)
t.EndLoadData()
prg.Add(sreader(0))
gnd.Add(sreader(4))
Else
prg.Add(sreader(0))
gnd.Add(sreader(4))
updated(7) += nxtPercentage
End If
End While
End If
sgetComm.Dispose()
sgetComm = Nothing
sreader.Close()
sreader = Nothing
Catch ex As Exception
' modify when going live'
lblDetails.Text &= "Error loading to table with get of sire" & Err.Description
End Try
End Using
GetPct(prg, gnd, nxtG, j)
End If
Next i
End Sub