I have an old web application written in ASP.Net 2.0 Web Forms. I use the Data Access Block in Enterprise Library and have recently updated to version 5.0. The application is tiered, ie, UI layer, Service Layer, Data Layer. It also uses SQL Server 2008 for the data storage.
I have recently noticed that the following error is appearing when I run the application and browse to particular pages.
Timeout expired. 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.
This tends to happen on pages that do a lot of separate reads from the database, maybe up to as many as 20 on one page.
Below shows snippets of my Data Access Class.
Public Class DataAccess
' create a private instance of the database factory
Private db As Database = DatabaseFactory.CreateDatabase()
Public Function ExecuteNonQuery(ByVal params() As SqlParameter, ByVal strSproc As String) As Integer
Dim intReturnValue As Integer = 0
Dim i As Integer
Dim cmd As DbCommand
cmd = db.GetStoredProcCommand(strSproc)
cmd.CommandTimeout = 120
For i = 0 To params.Length - 1
db.AddInParameter(cmd, params(i).ParameterName.ToString, params(i).DbType, params(i).Value)
Next
db.AddParameter(cmd, "return_value", DbType.Int32, ParameterDirection.ReturnValue, "", DataRowVersion.Default, 0)
db.ExecuteNonQuery(cmd)
intReturnValue = Int32.Parse(db.GetParameterValue(cmd, "#return_value"))
Return intReturnValue
End Function
Public Function ExecuteDataReader(ByVal params() As SqlParameter, ByVal SProc As String) As SqlDataReader
Dim i As Integer
Dim dr As SqlDataReader = Nothing
Dim cmd As DbCommand
cmd = db.GetStoredProcCommand(SProc)
cmd.CommandTimeout = 120
For i = 0 To params.Length - 1
db.AddInParameter(cmd, params(i).ParameterName.ToString, params(i).DbType, params(i).Value)
Next
dr = TryCast(DirectCast(db.ExecuteReader(cmd), RefCountingDataReader).InnerReader, SqlDataReader)
Return dr
End Function
Throughout my code, once I have finished with an SqlDataReader I always do something like this
If Not (drSource Is Nothing) Then
drSource.Close()
End If
Is there anything you folk can see that I am missing? Does it look like my code could be leaking connections or not closing properly?
I always thought the Garbage collector got rid of any open connections.
Any feedback or help would be greatly appreciated.
Thanks.
Your code is closing the data reader, but not the data connection associated with it.
Since your data reader is a SqlDataReader, it has a Connection property. You should be able to use that to close and dispose of the connection.
Related
I have the following code:
Dim da As SqlDataAdapter
Dim rst As DataRow = MyrstEdit("SELECT * FROM tblHotels WHERE ID = 19",, da).Rows(0)
rst("HotelName") = "My Cool"
rst("FirstName") = "Albert"
rst("City") = "Edmonton"
da.Update(rst.Table)
So, the above is nice and short. And it works rather nice.
And of course this being asp.net, then centralizing things like connection code (that I don't have to create over and over) is a also rather nice. And why bother with a connection during coding, so above reduces coding workload.
How then can I ensure the connection object is disposed and closed correctly?
From reading, since I do not open the conneciton, then
The Fill() does open, then close.
And I have to assume that the da.Update() ALSO must then by logic open, then close the conneciton.
However, I still should clean up the connection object after above is done.
Question:
Is disposing of the sql data adaptor object sufficient here to also dispose the connection object that the data adaptor is using?
eg:
da.Dispose()
The MyRstEdit routine is this:
Public Function MyrstEdit(strSQL As String,
Optional strCon As String = "",
Optional ByRef oReader As SqlDataAdapter = Nothing) As DataTable
' can pass custom connection string - if not passed, then default
If strCon = "" Then
strCon = GetConstr() ' global func to get application con string
End If
Dim mycon As New SqlConnection(strCon)
oReader = New SqlDataAdapter(strSQL, mycon)
Dim rstData As New DataTable
Dim cmdBuilder = New SqlCommandBuilder(oReader)
Try
oReader.Fill(rstData)
oReader.AcceptChangesDuringUpdate = True
Catch
End Try
Return rstData
End Function
So, the return sqlDataAdaptor object must be holding the connection, since the scope in above routine is limited.
So do I have to dispose the connection object?
Can I do this with the sqlAdaptor?
I can't dispose/close the connection object in above sub, since my da.Update() in the calling code still needs that connection until I do the update.
How then can I ensure the connection object is disposed and closed correctly?
Don't worry about it; it's not your job. DataAdapter makes it, DataAdapter will clean it up
However, I still should clean up the connection object after above is done
No, for the aforementioned reason
Is disposing of the sql data adaptor object sufficient here to also dispose the connection object that the data adaptor is using?
Yes, unless you have good reason to believe that Microsoft's code has a critical flaw and their classes will benefit from your code micromanaging the resources they create..
You can also read the reference source if you want to know what they do internally
The MyRstEdit routine is this:
It's hard to understand why it exists in that form; you'd be better off just passing a datatable around and creating dataadapters as and when you need them. MyRstEdit isn't well named; it doesn't seem to edit anything, it always overwrites the passed in adapter with stuff that a any passed in adapter might already know (the connstr and sql) and then doesn't really do anything that couldn't just be put to
Using da As New SqlDataAdapter("SELECT * FROM tblHotels WHERE ID = 19", GetConStr())
Dim dt as New DataTable
da.Fill(dt)
Dim rst = dt(0)
rst("HotelName") = "My Cool"
rst("FirstName") = "Albert"
rst("City") = "Edmonton"
New SqlCommandBuilder(da)
da.Update(rst.Table)
End Using
About the most useful thing it does is apply a command builder, but that's only a single line and only needed for an update..
Perhaps you could create an extension method that applies to a DataAdapter, that gets the first row, so you could say:
Using da As SqlDataAdapter("SELECT * FROM tblHotels WHERE ID = 19", GetConStr())
Dim rst = da.FirstRow()
rst("HotelName") = "My Cool"
rst("FirstName") = "Albert"
rst("City") = "Edmonton"
New SqlCommandBuilder(da)
da.Update(rst.Table)
End Using
But it isn't saving much over "just using it how MS intended", and there is still that block of "data columns accessed by string and hence intellisense can't help" in the middle.
If you're looking to find ways of making your SqlDataAdapter life easier it might be an opportunity to skip it and have a look at Dapper instead; a set of extension methods on a SqlConnection that map classes to and from:
Using c as New SqlConnection(GetConStr())
Dim h = Await c.SingleAsync(Of Hotel)("SELECT * FROM tblHotels WHERE ID = #id", New With { .ID = 19 } )
h.HotelName = "My Cool"
h.FirstName = "Albert"
h.City = "Edmonton"
Await c.ExecuteAsync("UPDATE tblHotels SET HotelName = #HotelName, FirstName = #FirstName, City = #City WHERE ID = #ID", h)
End Using
You still have to write the queries, but it's a one time op, or you could look at something like Dapper Contrib.. The main use here is that instead of being some DataRow object you access by "string column names" you have a first class VB.NET object - Hotel, with named typed proeprties, and dapper can create them from SQL queries and put their values directly into SQL parameters (another thing that is absent from your existing code)
This is the scenario:
I'm doing a web service in WCF and a client application in ASP.NET. The language is VB.NET.
I want a method than send "jobs" to the server. I'm trying to simulate this kind of jobs as long running processes that wait up to 20-30 seconds with thread sleeping and inserting a row into a JOBS table in the DB.
I want another method that polls the database every 5 seconds with client postbacks to get the jobs lists from the JOBS table (finished and currently running)
This is what i've got so far, both methods are working, except when a long running job is sleeping, then the client can't retrieve the list of jobs with another call. I've tried "PerCall" in the but it didn't work out. I suspect the thread is somewhat locking the service or maybe I have to use async calls. I'm using HttpBasicBinding at web.config ... I'm a little lost and I have not found any code doing something similar.
Here is the code in the service side:
iServiceJobs.vb
<ServiceContract()>
Public Interface IServiceJobs
<OperationContract(IsOneWay:=True)>
Sub SendJob(ByVal runTime As Integer, ByVal id As String)
<OperationContract>
Function GetJobsList() As List(Of ClassJob)
ServiceJobs.vb
Public Class ServiceJobs Implements IServiceJobs
Public SendJob(ByVal runTime As Integer, ByVal id As String) Implements IServiceJobs.SendJob
Dim connStr As String = "..."
Dim conn As New OracleConnection(connStr)
conn.Open()
Dim query As String = "INSERT INTO JOBS(...)"
Dim cmd As New OracleCommand(query, conn)
cmd.ExecuteNonQuery()
Threading.Thread.Sleep(runTime* 1000)
cmd = New OracleCommand(query, conn)
cmd.ExecuteNonQuery()
End Sub
Public Function GetJobList() As List(Of ClassJob) Implements IServiceJobs.GetJobsList
Try
Dim jobList As New List(Of ClassJobs)
Dim connStr As String = "..."
Dim conn As New OracleConnection(connStr)
conn.Open()
Dim query As String = "SELECT * FROM JOBS"
Dim cmd As New OracleCommand(query, conn)
Dim dr As OracleDataReader
Dim job As ClassJob
dr = cmd.ExecuteReader
While dr.Read
job = New ClassJob
job.id = dr(0)
job.lock = dr(3)
...
jobList.Add(job)
job = Nothing
End While
Return jobList
Catch ex As Exception
Return Nothing
End Try
End Function
End Class
The code in the client is very simple, just two buttons, one with a ws call for insert jobs and another to get the job list.
I'm open to any suggestion on how to do a better implementation of this scenario.
EDIT:
I've tried
<ServiceBehavior(ConcurrencyMode:=ConcurrencyMode.Multiple, InstanceContextMode:=InstanceContextMode.PerCall)>
But it doesn't work, GetJobList() returns Nothing while SendJob() is working on this thread.
SOLVED: Apparently, I was using an outdated version of Oracle libraries. When I used Oracle.ManagedDataAccess from NuGet everything went OK.
SOLVED: Apparently, I was using an outdated version of Oracle libraries. When I used Oracle.ManagedDataAccess from NuGet everything went OK.
I've got various web apps (containing WCF services) in IIS under the default website. As long as they are all running in the same app pool they can access a shared isolated storage file no problem.
However, once I move them to different app pools I get "System.IO.IsolatedStorage.IsolatedStorageException: Unable to create mutex" when one tries to access a file created by another. They are all running under NetworkService user. I tried GetUserStoreForAssembly and GetMachineStoreForAssembly all with the same result. Any ideas why they couldn't use a shared file?
I made sure to close the stream and even dispose it in case one was holding onto it, but I am running a simple test where one service writes it, then another tries to read from it later, and it always fails.
Also, I am accessing the isolated store from a signed assembly.
Does anybody have any ideas?
Here is the code:
Private Sub LoadData()
Dim filename = FullFilePath(_fileName)
Dim isoStorage As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForAssembly()
' Tried GetMachineStoreForAssembly, same failure
isoStorage.CreateDirectory(ROOT_DIRECTORY)
If (isoStorage.GetFileNames(filename).Length = 0) Then
Return
End If
Dim stream As Stream = New IsolatedStorageFileStream(filename, FileMode.OpenOrCreate, isoStorage)
If stream IsNot Nothing Then
Try
Dim formatter As IFormatter = New BinaryFormatter()
Dim appData As Hashtable = DirectCast(formatter.Deserialize(stream), Hashtable)
Dim enumerator As IDictionaryEnumerator = appData.GetEnumerator()
While enumerator.MoveNext()
Me(enumerator.Key) = enumerator.Value
End While
Finally
stream.Close()
stream.Dispose()
stream = Nothing
End Try
End If
End Sub
Public Sub Save()
Dim filename = FullFilePath(_fileName)
' Open the stream from the IsolatedStorage.
Dim isoFile As IsolatedStorageFile = IsolatedStorageFile.GetUserStoreForAssembly()
' Tried GetMachineStoreForAssembly, same failure
Dim stream As Stream = New IsolatedStorageFileStream(filename, FileMode.Create, isoFile)
If stream IsNot Nothing Then
Try
Dim formatter As IFormatter = New BinaryFormatter()
formatter.Serialize(stream, DirectCast(Me, Hashtable))
Finally
stream.Close()
stream.Dispose()
stream = Nothing
End Try
End If
End Sub
Looks like it was a trust issue.
After adding the assembly accessing the isolated storage file to the gac it magically worked as everything in the gac has full trust set automatically.
This works for me, but it might not always be an option to do this for other solutions. Check out the .NET Framework caspol utility if this is the case.
Hope this helps somebody! It was a huge pitafor me.
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
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.
Okay this question could either be very broad or very specific because I am not sure if I am going about this in a fundamentally wrong way or if I am close to correct.
First an overview: What I am trying to do it create a server application for all of the clients in my organization to connect to. I think the best way to do this is to use a web service. Please correct me if I am wrong!
Anyway, if I use a web service I need the web service(server) to connect to the database. In MS Visual studio when you add a web service project the data menu disappears and you can't add a data source to the project. There may be a workaround for this by hand coding this, but I am not sure how to do it. This is my first time working with a web service and ASP.NET so I am a real noob in this area.
Any help would be greatly appreciated!!!
Add your database connection string to the <connectionStrings/> section of the web service web.config file. Check this web site for a list of the most common database connection strings: Connectionstrings.com
You would use standard ADO.Net commands and SQL statements, rather than using the dataset designer. Example (IN VB)
<WebMethod()> _
Public Function DoesOpenCallExist(ByVal CustID As String, ByVal CallType As String, ByVal SubCallType As String) As Boolean
Dim returnvalue As Boolean = False
' first, entry validation
' snip - code deleted
Dim conn As New System.Data.SqlClient.SqlConnection
conn.ConnectionString = System.Configuration.ConfigurationManager.ConnectionStrings("HEATConnectionString").ConnectionString
Dim cmd As New SqlClient.SqlCommand
cmd.Connection = conn
cmd.CommandType = CommandType.StoredProcedure
cmd.CommandText = "sp_GetCallCount"
cmd.Parameters.AddWithValue("#CustID", CustID)
' Etc...
Try
conn.Open()
returnvalue = cmd.ExecuteScalar() > 0
Catch ex As Exception
Throw New Exception(ex.ToString())
Finally
conn.Close()
End Try
Return returnvalue
End Function
*This should be done
web.config file*
here the datsource is the servername,initial catlog is the databasename and the userid ur sql userid and the password is as same.
And then in the class we want to get connect with the database......
****class.cs****
public class connect
{
public static SqlConnection con()
{
String con= ConfigurationManager.AppSettings["connections"].ToString();
SqlConnection cn = new SqlConnection(con);
cn.Open();
return cn;
}
}
here the connection is the keyname......
ok i think its sufficient............