InvalidOperationException: Timeout - recursive DB access - asp.net

Question

currently I have a serious problem with one of my web applications which runs into a Timeout Exception around half a dozen times a day.
Error: "The timeout period elapsed prior to obtaining a connection from the pool. This may have occurred because all pooled connections were in use and max pool size was reached".
After a lot of googling I found out that the problem has something to do with unclosed connections. So I checked all functions that access the database in any way until I stumbled upon this one:
Private Sub getOrgas(ByVal orgID As String)
Dim Id = orgID
orgColl.Add(Id)
While (Not IsNothing(Id))
Dim conn = Database.DbWrapper.GetConnection(1, Integration.Mandanten.DatabaseType.AddonSQL)
Dim paras As New HashSet(Of System.Data.Common.DbParameter)
Dim orgatmp As String
paras.Add(New SqlClient.SqlParameter("#Id", orgID))
Dim dr = Database.DbWrapper.GetDataReaderFromStoredProcedure("stp_Orgas_Get", paras, conn)
While dr.Read
If Not valueInColl(CStr(dr(0))) Then
orgatmp = dr(0).ToString
orgColl.Add(orgatmp)
getOrgas(orgatmp)
End If
End While
dr.Close()
conn.Close()
Id = Nothing
End While
End Sub
As you can see this function executes a stored procedure and runs the results through a while loop where it calls the function again if a specific condition -valueInColl-. Now in that way it is possible that there are 20 or more open connections. It has nothing to do with the timeout-value which is set via the GetDataReaderFromStoredProcedure to 600 which actually should be enough. To be sure I doubled the value and will roll it out this evening. I'll see whether that helped within the next day then.
I believe the problem is that there are too many open connections at the same time, because of the recursive function, but I have no clue how to solve this.
I couldn't find anything as to how to edit the max connections. I'm not even entirely sure where have to set it. Is it the IIS, the DB itself or is it a programming-parameter (VB.net/ASP.NET).
Would be nice if you guys could help me out here.
[EDIT]
Ok, somebody had the idea to reuse the connection variable, but this won't work as the datareader is still running. As long as it is not closed I can't reuse the connection in any way and I can't close the datareader, because I might lose data if I do so. The while-loop for dr.read hasn't ended, yet ..
On the other hand I deleted the (pretty much useless) outer while and used an If-clause in exchange:
Private Sub getOrgas(ByVal orgID As String, ByVal con As DbConnection)
Dim Id = orgID
Dim conn As DbConnection
Dim tmpOrga As String
orgColl.Add(Id)
If Not IsNothing(Id) Then
If IsNothing(con) Then
conn = Database.DbWrapper.GetConnection(1, Integration.Mandanten.DatabaseType.AddonSQL)
Else
conn = con
End If
Dim paras As New HashSet(Of System.Data.Common.DbParameter)
paras.Add(New SqlClient.SqlParameter("#Id", orgID))
Dim dr = Database.DbWrapper.GetDataReaderFromStoredProcedure("stp_Orgas_Get", paras, conn)
While dr.Read
If Not valueInColl(CStr(dr(0))) Then
tmpOrga = dr(0).ToString
orgColl.Add(tmpOrga)
getOrgas(tmpOrga, conn)
End If
End While
dr.close()
conn.Close()
Id = Nothing
End If
End Sub

Answer 1

Is there any reason you cannot refactor things so that each recursion uses the same db connection?
I am not a VB coder but I would tackle it as follows
Change getOrgas() to take a connection parameter defaulting to 'nothing'.
Change the Dim conn line to if IsNothing(connParameter) conn = GetConnection() else conn := connParameter;
Change your recursion line to getOrgas(orgatmp, conn);
Test the F%%%% out of it.
I have just noticed the outer While Loop. Is it there just to confuse you ? How many times will it execute ? ...
I did wonder about the datareader -
try this - I see that your datareader needs to close before you recurse, so close it.
in pseudocode -
dim locallist = new list();
while dr.read
{
LocalList.Add dr.thing;
}
dr.close;
foreach(thing in locallist)
{
if Not ValueInColl(thing) Then
CallYourFunctionTRecursively()
end if;
}
Are you with me ?
If you are trying to put together all the members of a family then it depends which database system you are using how it is done, but look up 'Heirarchical queries' in your documentation.