FIX: Marshaling ADO Recordset Out-of-Process Causes Small Memory Leak

• Remote Data Service for ADO versions 1.0, 2.1 SP1
• Microsoft Data Access Components version 2.1 SP1

SYMPTOMS

When an ADO recordset is marshaled out-of-process from a COM server, a small leak in Private Bytes occurs in the COM server's process space.

This leak occurs when using either a disconnected ADO recordset or a recordset created with the RDS DataFactory.

CAUSE

The leak is caused by ADO internally making an incorrect call to AddRef() on a Stream pointer within MarshalInterface.

STATUS

A supported fix that corrects this problem is now available from Microsoft, but it has not been fully regression tested and should be applied only to systems experiencing this specific problem. If you are not severely affected by this specific problem, Microsoft recommends that you wait for the next Microsoft Data Access Components 2.1 SP2 that contains this fix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

MORE INFORMATION

Steps to Reproduce Behavior

1. Create an Executable project in Visual Basic that will be the server application. Name the project LeakEXE, and within it, create a class module named LeakRS. Use the following code within the LeakRS class:

   
   Option Explicit
   
   Function GetRS() As ADODB.Recordset
   Dim rs As ADODB.Recordset
       
       On Error Resume Next
       Set rs = New ADODB.Recordset
       rs.Fields.Append "x", adInteger
       rs.Open
       rs.AddNew
       rs.Fields(0).Value = 1
       rs.Update
       rs.MoveFirst
       Set GetRS = rs
       
   End Function 




2. Next, create a client project in Visual Basic, using the following code:

   
   
   Sub OutofProcLeak()
   Dim x As New LeakEXE.LeakRS
   Dim rs As ADODB.Recordset
   
   For i = 0 To 200000
       Set rs = x.GetRS
       Debug.Print Str(i)
       DoEvents
   Next
   
   Set rs = Nothing 




3. Run the client application. Use the Windows NT Performance Monitor to watch Private Bytes counter for object Process using instance LeakEXE.exe.

Additional query words: ado rds out of process recordset memory leak small

Keywords : kbADO210fix kbRDS210fix kbMDAC210fix
Version : WINDOWS:1.0,2.1 SP1
Platform : WINDOWS
Issue type : kbbug