Debugging Memory Problems

Working in a language like C or C++ exposes you to all the glory and misery of memory management. The introductory programming classes at NYU are now taught in Java, and from talking to people I get the impression that most high school programming classes are as well. It's interesting to me that people can be in their third or fourth year of a computer science degree without ever having seen what happens when you double-free a pointer, but clearly this is now the majority case.

We talked about the fundamental problem of memory management, and the advantages is has over using a garbage-collected language and VM environment like Java (or Perl, or Python, or Ruby, or...) which with the power available on modern machines are honestly fairly thin. In most cases the only reasons to give up the benefits of automatic memory management involve performance or resource constraints related to embedded or similarly constrictive environments.

That said, we went over a few historical ways of finding memory leaks, and the conceptual underpinnings of automatic code annotation. In particular we talked about strategies for recording and monitoring the state of various regions of memory, and implementation details in C++ for doing this sort of thing yourself. When it comes down to it, though, the right thing to do is use valgrind. I'd have more to say, but the lecture notes are returning 404s so the details aren't available to me to go over.