Alex Rivera | Logout

Any reason to overload global new and delete?

Asked 2009-07-20T09:11:31.773
55

Unless you're programming parts of an OS or an embedded system are there any reasons to do so? I can imagine that for some particular classes that are created and destroyed frequently overloading memory management functions or introducing a pool of objects might lower the overhead, but doing these things globally?

Addition
I've just found a bug in an overloaded delete function - memory wasn't always freed. And that was in a not-so memory critical application. Also, disabling these overloads decreases performance by ~0.5% only.

c++ memory-management overloading
Edit
Report

1 Answer

4

Overloading new & delete makes it possible to add a tag to your memory allocations. I tag allocations per system or control or by middleware. I can view, at runtime, how much each uses. Maybe I want to see the usage of a parser separated from the UI or how much a piece of middleware is really using!

You can also use it to put guard bands around the allocated memory. If/when your app crashes you can take a look at the address. If you see the contents as "0xABCDABCD" (or whatever you choose as guard) you are accessing memory you don't own.

Perhaps after calling delete you can fill this space with a similarly recognizable pattern. I believe VisualStudio does something similar in debug. Doesn't it fill uninitialized memory with 0xCDCDCDCD?

Finally, if you have fragmentation issues you could use it to redirect to a block allocator? I am not sure how often this is really a problem.

answered 2009-07-30T20:42:36.180

Your Answer