1 – Nd113 Story 1 V1

So now that you suffer through all these wonderful things like, pointers, and memory allocations. So, let me tell you the story of the worst self-driving car bucket I ever caused and had to fix. Took me many months to find it. Okay. So we are, now back in 2005 driving Stanley, the self-driving car, through the Mojave Desert. And initially, we had one computer on board, and he was fine. And then the computer was overloaded, so we put a second computer on board. And as a result, as we found out every 40 miles, the robot would see a fake wall of obstacle in front of it, engage in a crazy, crazy swerve, and almost kill us, but felt like killing us. And then we had to intervene and take over. And we knew the race was about 120 miles long. So every 40 miles the robot would do this, we would not finish the race. So what was it? So you’re looking at the robot advance a mile, it could be there and fine, and second, it doesn’t. And we were flabbergasted. What ended up being is, we had put in a timer for how all the data is. They would give us a bound on how big an obstacle is. Let’s take this for granted for now. In moving to two computers, we found that the clocks ran different speeds. Pretty common in many two computers. And we installed computer software, C++, to synchronize these clocks. And every one so often, the synchronization would set a clock value back. Now a test that would be contingent on the time elapsed would not have a negative number because timeless was negative. And that in conjunction with the vehicle bumping up and down over a little hump caused a fake obstacle. Now, that was brutal. It took us literally months to find it. And we drove every day, and every 40 miles or so we got this effect, and we couldn’t figure out what’s going on. Now, I’m telling you this story because, when you dive and become a software engineer, every little detail matters. And you have to understand how memory allocation works, how pointers work, how data structures work, because if you don’t, and you allocate memory twice, or you forget to free it, at some point, you’re self-driving car will fatally commit suicide, okay? So, thanks for sticking with us, and I hope you appreciate we just learned.

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