Why does my Thread hang?

Im developing a windows application (not Internet based) using Visual Studio 2008 and Visual C#. Its an MDI application.

The thread enters this "getTriggerWaveform_DLL" function (shown below) but very occasionally never  returns from it. It just vanishes into a black hole. I cant set debugging for this function either. Ive tried and I asked on this forum but the solutions proposed dont work. The function is compiled into a DLL. The thing is Id expect it to at the very least throw an exception back to the calling statement.

Can anyone suggest a modification to this routine such that I should always get an exception thrown back if something goes wrong?

extern "C" __declspec(dllexport) double* getTriggerWaveform_DLL(long channelNo, long noOfPoints, double* timeIncrement, double* startTime) throw(exception) {
      double* results = new double[noOfPoints];

      try{
            theDSO -> getTriggerWaveform(channelNo, noOfPoints, results, timeIncrement, startTime);
      } catch(DSOCPPException e){
            setLastException(e.what());
            throw e;
      }
      return results;
}
rangers99Asked:
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evilrixConnect With a Mentor Senior Software Engineer (Avast)Commented:
How do you know that getTriggerWaveform ever returns? How do you know it's a C++ exception being thrown? It might be a structured exception being thrown, not a C++ exception. For this you need to look at Structured Exception Handling (SEH).

http://msdn.microsoft.com/en-us/library/ms680657(VS.85).aspx
http://msdn.microsoft.com/en-us/library/8c522k35.aspx

Also, exceptions should NEVER be allowed to cross an API boundary. The calling langauge may not be the same as the libraries language. So, if getTriggerWaveform was a managed code DLL, for example, and it throws a managed exception across the API boundary you have absolutely no chance of catching it using unmanaged C++.
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evilrixConnect With a Mentor Senior Software Engineer (Avast)Commented:
Additional...

catch(DSOCPPException e)

NEVER catch by value... if it's a polymorphic exception class you'll slice it. Also, you'll copy the exception object (wasteful). Always catch by reference and catch using the highest type int he class hierarchy that you can so as to be able to discern the exception type.

catch(std::runtime_error const & e)
{
}
catch(std::exception const & e)
{
}

Do you expect DSOCPPException from this function?
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rangers99Author Commented:
evilrx
Thanks for those  answers. Im inexperienced at this but Ill read the those links. cheers.
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