BUG: Memory Leak When You Load and Unload the SQL Server ODBC Driver or OLE DB Provider (313883)

The information in this article applies to:

Microsoft OLE DB Provider for SQL Server 2000 2000.80.194
Microsoft OLE DB Provider for SQL Server 2000 2000.80.380.0
Microsoft OLE DB Provider for SQL Server 2000 2000.81.7713.0
Microsoft ODBC Driver for SQL Server 2000 2000.80.194
Microsoft ODBC Driver for SQL Server 2000 2000.80.380
Microsoft ODBC Driver for SQL Server 2000 2000.81.7713.0
the operating system: Microsoft Windows NT 4.0
the operating system: Microsoft Windows NT 4.0 SP6a

This article was previously published under Q313883

SYMPTOMS

An approximately 4-kilobyte (KB) memory leak is encountered when you use Microsoft Windows NT 4.0 Service Pack 6a (SP6a) to load and unload Microsoft SQL Server client components (the ODBC driver or OLE DB provider). The following Visual Basic code produces this behavior:

Public Sub Main()
   Dim cn as ADODB.Connection

   While (1)
      Set cn = New ADODB.Connection
      cn.Open "Driver={SQL Server};SERVER=myserver;DATABASE=mydb;UID=GuestAccount"
      cn.Close
      Set cn = Nothing
   Wend
End Sub

CAUSE

This behavior is caused by a low-level system leak. It occurs only during the loading and unloading of the Dbnetlib.dll file.

RESOLUTION

If you must run your application on Windows NT 4.0 SP6a, it is recommended that you ensure that one of the following conditions is true:

An open connection is maintained for the duration of the application.

-or-
You call the Win32 API LoadLibrary function to load Dbnetlib.dll, and keep it loaded for the duration of the application.

NOTE: When you turn on ODBC connection pooling or OLE DB resource pooling for the application, this lessens the amount of leakage, because connections are pooled and left open even though the application has closed the connection.

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.

MORE INFORMATION

This issue does not occur on Microsoft Windows 2000 or Microsoft Windows XP-based systems.

Modification Type:	Major	Last Reviewed:	12/5/2003
Keywords:	kbBug KB313883