Q265792: DB2OLEDB Leaks Memory When Stored Proc Returns adLongVarChar

Article: Q265792
Product(s): Microsoft SNA Server
Version(s): WINDOWS:4.0 SP3
Operating System(s): 
Keyword(s): kbSNA400sp4fix kbSNA400PreSP4fix
Last Modified: 12-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, version 4.0 SP3 
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SYMPTOMS
========

If an application uses the Microsoft OLE/DB for DB2 Provider to receive a large
adLongVarChar parameter (for example, 25,000 bytes) from a stored procedure
call, the Db2oledb.dll and Db2serv.exe processes may leak memory.

The memory leak in Db2serv.exe occurs whenever the stored procedure call
completes, and is visible in Performance Monitor by viewing the Private Bytes of
the application process and the Db2serv.exe process. When the application ends,
the Db2serv.exe memory never decreases. Over time, Db2serv.exe will grow
indefinitely in size. If the stored procedure call is implemented in a COM
object and invoked repeatedly from a Visual Basic program, the following error
message may occur:

  80004005 (unspecified error)


CAUSE
=====

This is caused by a problem in the DB2 Provider's support for stored procedures.

RESOLUTION
==========

To resolve this problem, obtain the latest service pack for SNA Server 4.0. For
additional information, please see the following article in the Microsoft
Knowledge Base:

  Q215838 How to Obtain the Latest SNA Server Version 4.0 Service Pack



STATUS
======

Microsoft has confirmed this to be a problem in Microsoft SNA Server 4.0 SP3.

This problem was first corrected in SNA Server 4.0 Service Pack 4.

MORE INFORMATION
================

The following Visual Basic sample is used to reproduce the problem. The data
link properties in the UDL file point to an IBM DB2 system configured with a
stored procedure name of SPSAMPLE, which returns an adLongVarChar parameter of
25,000 bytes.

  Attribute VB_Name = "Form1"
  Attribute VB_GlobalNameSpace = False
  Attribute VB_Creatable = False
  Attribute VB_PredeclaredId = True
  Attribute VB_Exposed = False
  Private Sub Command1_Click()

  Dim recset1 As New ADODB.Recordset
  Dim connection1 As New ADODB.Connection
  On Error GoTo ErrorHandler

  'Can see memory usage increase with each repetition of this test
   For x = 0 To 500
      
       connection1.ConnectionString = "File Name=C:\DB2.UDL" 'Connection
       connection1.CursorLocation = 2
       connection1.Open
          
       Set cmd = New ADODB.Command
       cmd.Prepared = True
       cmd.CommandText = "CALL SPSAMPLE (?,?,?)"
       cmd.CommandType = adCmdText
         
       ' Get parameter value and append parameter.
       Set param = cmd.CreateParameter("foo1", adLongVarChar, adParamOutput)
       param.Size = 25002
       cmd.Parameters.Append param
          
       ' Get parameter value and append parameter.
       Set param = cmd.CreateParameter("foo2", adInteger, adParamOutput)
       param.Value = 0
       param.Size = 4
       cmd.Parameters.Append param
          
       ' Get parameter value and append parameter.
       Set param = cmd.CreateParameter("foo3", adInteger, adParamOutput)
       param.Value = 0
       param.Size = 4
       cmd.Parameters.Append param
         
       ' Create recordset by executing the command.
       Set cmd.ActiveConnection = connection1
       cmd.Execute
      
       'The parameter should consist of "VARIABLE CHARACTER STRING OF 25000
       'BYTES IN LENGTH" repeated 499 times. The very last piece of text in
       'the varchar is "THE VERY VERY VERY LAST  CHARACTER STRING".
       'Debug.Print Len(cmd.Parameters(0).Value)
       'Debug.Print cmd.Parameters(0).Value
          
       'Clean Up
       Set param = Nothing
       Set cmd = Nothing
       Set connection1 = Nothing
      
  Next x
    
  EndMsg = MsgBox("Test Finished", vbOKOnly, "SPSAMPLE")
     
  Exit Sub
      
  ErrorHandler:
      ' Output error message
          MsgBox Error

  End Sub

Additional query words:

======================================================================
Keywords          : kbSNA400sp4fix kbSNA400PreSP4fix 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ400SP3
Version           : WINDOWS:4.0 SP3
Issue type        : kbbug
Solution Type     : kbfix

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