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


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This article was previously published under Q230487

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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 if you are using versions of MDAC earlier than 2.1 sp2.

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Cause

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

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Status

This problem has been fixed in Microsoft Data Access Components 2.1 and later. You may download the latest version of Microsoft Data Access Components from the following site:

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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. Set a reference to the Microsoft ActiveX Data Objects Library. 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. Then, set a reference to the ActiveX EXE and to Microsoft ActiveX Data Objects Library.
    
    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.

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Keywords: kbhotfixserver, kbado210fix, kbbug, kbdatabase, kbfix, kbmdac210fix, kbmdacnosweep, kbqfe, KB230487

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Article Info
Article ID : 230487
Revision : 9
Created on : 5/17/2007
Published on : 5/17/2007
Exists online : False
Views : 380