Knowledge Base

FIX: Problems with Asynchronous Break on Multiprocessor Machines

Article ID: 198839

Article Last Modified on 2/24/2004

Microsoft Visual C++ 5.0 Enterprise Edition
Microsoft Visual C++ 6.0 Enterprise Edition
Microsoft Visual C++ 5.0 Professional Edition
Microsoft Visual C++ 6.0 Professional Edition
Microsoft Visual C++ 6.0 Standard Edition

This article was previously published under Q198839

SYMPTOMS

Debugging a multithreaded application on a multiprocessor machine may show that at some point the asynchronous break fails after a breakpoint is encountered more than once. The CPU usage shows 100 percent busy for all processors in the application that is being debugged. However, this application is not running any useful code and you can not break into it.

In some cases, you may find that the debugger does not break at a breakpoint.

CAUSE

This occurs because of the way that a breakpoint is marked and resumed in a multithreaded application, which affects thread resume operations in a multiprocessor machine.

STATUS

Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article. This bug was corrected in Visual Studio 6.0 Service Pack 3. For more information about Visual Studio service packs, please see the following articles in the Microsoft Knowledge Base:

194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

Keywords: kbbug kbfix kbdebug kbvs600sp3fix KB198839