BUG: ADO Application May Hang When You Use OLE DB Provider for DB2 (276200)

SYMPTOMS

An Active Data Object (ADO) application that leverages the OLE DB Provider for DB2 may intermittently stop responding (hang) when the data source is configured to use the Transfer Control Protocol/Internet Protocol (TCP/IP) transport to the remote system.

The following Visual Basic sample code shows a typical code-loop scenario in which this problem may occur:


 ...
 ...
   If (rsChrgs.State And adStateOpen) = adStateOpen Then

        While Not bDone
        
            vaRows = rsChrgs.GetRows(100)  
            nTotalRows = UBound(vaRows, 2)
            For nRow = 0 To nTotalRows
                DoEvents
                If bCancel Then Exit Function
            Next
            bDone = (nTotalRows < 99)
        Wend
    
    End If
 ...
 ...

A call to the GetRows function may block indefinitely so that control is not returned to the calling function. The application hangs at this point.

CAUSE

When the OLE DB Provider for DB2 receives a Distributed Data Management (DDM) General Data Stream (GDS) header that is split across multiple TCP/IP packets, the provider does not work correctly (fails). No errors are reported to the Microsoft Windows NT Application Event Log when the provider fails.

RESOLUTION

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

215838 How to Obtain the Latest SNA Server Version 4.0 Service Pack

STATUS

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

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