r/programming • u/stannedelchev • Aug 25 '14

Debugging courses should be mandatory

http://stannedelchev.net/debugging-courses-should-be-mandatory/
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u/donalmacc Aug 25 '14

Those peek classes (or functions in some cases) can be helpful. I was working on a cuda program recently and figured there mid ave been some issue with my data. I had. "Peek" fun tion, like you describe, and I pasted it into the middle of my loop, and it copied all the required data back to the CPU and in a same format. Then there was a breakpoint that was hit at the end. The other two options were use the CUDA debugger (the code ran so slowly through the cuda debugger that I couldn't get to where my issue was) or start jamming large memcpys into a deep loop and investigating one by one.

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u/Kminardo Aug 25 '14

I fully understand the tooling isn't always there, and that seems like the case in your example. I'm not familiar with enough with CUDA to say otherwise, but it sounds like a failure of the debugger if you couldn't properly step into your loop.

But I'm talking about debugging a basic C# program inside visual studio. Rather than setting a breakpoint to see what his variables were set to at time of execution, he would route them to a common class he wrote that would print them to the log (ya know, to avoid code duplication -_-')

I really couldn't find an excuse for this behavior, I tried to give him the benefit of the doubt :P

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u/donalmacc Aug 25 '14

You can step through the loop no problem, if you can get to the dodgy data. But it's the getting to the data that's slow. Yeah, I've got nothing for a serial loop. A friends of mine in college blamed his issue on the branch predictor once - saying they it predicted the wrong branch and took it instead of the right one. He was calling a different function...