D.3 Debugging Threads on Windows NT Systems

The WinDbg Debugger, provided with the Windows NT Software Development Kit (SDK), provides support for debugging a threaded program. When working with DECthreads in WinDbg, be aware that terminating a thread with pthread_exit(), cma_exit_normal(), or cma_exit_error() raises an exception as a normal part of the exiting process. Unless you explicitly tell WinDbg to ignore this exception, it catches the exception and stops execution. To allow the thread to exit properly and your application to continue, use the WinDbg gn (go not handled) command. This command tells WinDbg to ignore the exception.

WinDbg also stops at each DECthreads exception block for this exception and has to be continued using the WinDbg gn command until the thread's stack is completely unwound. The exception used by DECthreads for thread rundown is 0xC1380034.

DECthreads also generates an exception in a thread as a normal part of thread cancellation. When cancelling a thread with pthread_ cancel() or cma_thread_alert(), an exception value of 0xC1380034 is raised. This exception should be allowed to propagate all the way to the base of the thread's stack. If WinDbg halts execution of the program and indicates that this exception is being raised, use the WinDbg gn command to allow the exception to continue.