Microsoft KB Archive/883715

= ODBC32.dll file causes a deadlock when loading an MFC extension DLL =

Article ID: 883715

Article Last Modified on 5/18/2007

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APPLIES TO


 * Microsoft Data Access Components 2.8, when used with:
 * Microsoft Windows XP Professional

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SYMPTOMS
You have a multi-threaded application that uses the ODBC32.dll file and the ODBCCR32.dll file. When the ODBC32.dll file tries to load a Microsoft Foundation Classes (MFC) extension DLL, you notice a deadlock in the application.



CAUSE
The ODBC32.dll file does not use the AfxLoadLibrary function to load the ODBCCR32.dll file. By design, the ODBC32.dll file loads the ODBCCR32.dll file, and the ODBCCR32.dll file gains the NTDLL loader lock and then tries to gain the MFC global lock. This may cause a permanent deadlock in a multi-threaded application.



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

322389 How to obtain the latest Windows XP service pack



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section. This problem was first corrected in MDAC 2.8 Service Pack 1. MDAC 2.8 Service Pack 1 is included with Windows XP Service Pack 2 (SP2).



MORE INFORMATION
According to MFC rules, an MFC extension DLL must be loaded by using the AfxLoadLibrary function. The reason for this rule is that an MFC Extension DLL makes calls to the AfxLockGlobals function internally from the dllmain function. Therefore, the core purpose of the AfxLoadLibrary function is to enforce the order of the locks to avoid deadlock situations.

