PATCH: Out of Memory Error w/ AddNew/Update on Dynaset/Table

ID: Q124709

The information in this article applies to:

Professional Edition of Microsoft Visual Basic for Windows, version 3.0

SYMPTOMS

Performing an AddNew and then and Update method on a table or dynaset causes the Jet database engine to allocate a small amount of memory that is not released until the Jet database engine is unloaded from memory. Therefore, programs that perform many Updates over a long period of time without unloading the Jet database engine will eventually result in an "Out of Memory" error.

RESOLUTION

There are two possible workarounds:

Update Vbdb300.dll to version 3.00.0530, dated 1 Feb 95 by downloading Vbdb300.exe. You can find Vbdb300.exe, a self-extracting file, on these services: The following file is available for download from the Microsoft Download Center. Click the file name below to download the file:

Vbdb300.exe

For more information about how to download files from the Microsoft Download Center, please visit the Download Center at the following Web address

http://www.microsoft.com/downloads/search.asp

and then click How to use the Microsoft Download Center.

NOTE: This version of the Vbdb300.dll does require the VB/Access compatibility layer (Comlyr.exe) and the updated Jet engine in the Access Service Pack (Accsvc.exe in the GO MSACCESS forum).

DISCLAIMER: The version of Vbdb300.dll (hereinafter the "Product") is being released as a patch (the "Patch") in order to fix a specific problem a few customers are experiencing with Microsoft Visual Basic 3.0. This Patch has been tested comprehensively to ensure that no errors or additional problems are introduced into the Product during normal usage. However, in order to release this Patch as quickly as possible, it has not have been subjected to the same series of rigorous functional and regression tests that are used for regular production products. Consequently, this Patch should be installed only if you are experiencing the specific problem mentioned above, and not applied indiscriminately. Use of this Patch is governed by all of the provisions of the Microsoft End User Software License Agreement included with the Product, as if it were the Product.

In addition, the Patch is provided to you at no additional charge. Microsoft Corporation owns all right, title and interest in and to the Patch.

Copyright 1995 Microsoft Corporation, All Rights Reserved.

-OR-

Periodically shell to another Visual Basic program that does not use the Jet database engine to unload the database application. This will cause all of the memory held by the Jet database engine to be released back to the system. You can then restart your application from the non-database program.

STATUS

This bug in Microsoft Visual Basic for Windows version 3.0 was corrected with Vbdb300.dll version 3.00.0530 dated 1 Feb 95.

MORE INFORMATION

This problem is not corrected by using the Microsoft Access 2.0/Visual Basic 3.0 Compatibility Layer; nor is it corrected by using the Microsoft Access version 2.0 Service Pack.

Steps to Reproduce Behavior

NOTE: You will need the older version 3.00.0529 of Vbdb300.dll and the Professional Edition of Visual Basic to reproduce the problem outlined below.

Create a new project. Form1 is created by default.

Add a label control to Form1.

Enter the following code for Form1:


   'Enter the following lines as one line

   Declare Function GetFreeSpace Lib "kernel" (ByVal flag As Integer) _
      As Long

   Sub Form_Activate ()
      Dim lngStartMem As Long
      Dim lngUsedMem As Long
      Dim lngRec As Long
      Dim strMsg as String
      Dim dbBiblio As Database
      Dim dsAuthors As Dynaset

      Label1.Caption = "Initializing..."
      Label1.Refresh

      Set dbBiblio = OpenDatabase("biblio.mdb")
      Set dsAuthors = dbBiblio.CreateDynaset("Authors")
      lngStartMem = GetFreeSpace(0)

      BeginTrans
      For lngRec = 1 To 100000
         dsAuthors.AddNew
         dsAuthors("Au_ID") = lngRec + 100
         dsAuthors("Author") = "Doe, John"
         dsAuthors.Update
         If lngRec Mod 500  = 0 Then
            CommitTrans
            lngUsedMem = lngStartMem - GetFreeSpace(0)
            strMsg = "Records: " & CStr(lngRec) & Chr$(13) & Chr$(10)
            strMsg = strMsg & "Used: " & CStr(lngUsedMem)
            Label1.Caption = strMsg
            Label1.Refresh
            BeginTrans
         End If
      Next
      CommitTrans

      dsAuthors.Close
      dbBiblio.Close
   End Sub

Run the program. The "Used:" line of the label tells how much memory has been allocated from the global memory heap. This memory is not recovered until you exit from Visual Basic.

Additional query words: 3.00 leak low adding comlyr accsvc

Keywords : kbpatch buglist3.00 APrgDataAcc
Version :
Platform : WINDOWS
Issue type :