使用AutoZone垃圾收集器

Question

Has anyone tried to use the autozone garbage collector from Apple? Or can you point to a good and configurable one usable with C++?

edit: I work on decision diagrams (like BDD), so I would like to test if managing the memory with a garbage collector is efficient in this case.

edit 2: To be more precise, when implementing a library for decision diagrams, you HAVE TO implement a garbage collector. In fact, I already did this for my library, but it represents more or less 25% of the code. And it is the most complicated part :-) So yes, I want a garbage collector :-) And yes, I already use RAII techniques. And, finally, I can not afford the cost of a shared_ptr, because I store billions objects which need to be garbage collected.

Answer 1

Have you already analyzed if you really need an implicit garbage collection library? are you sure it is not just java (or Objective C, ...) nostalgia?

That is not natural in C++, so you will probably get into more problems than you solve. Actual implementations are mostly used in experimentation tests, and not for production apps. The best way to squeeze the potential of a language is to do things the way are tackled in that language.

Check first if explicit garbage collection (boost::shared_ptr and friends ) cover your needs, and avoid introducing complexity when possible.

After Alexandre edit 2: Magic does not exist I'm afraid. Why do you think a garbage collector will be more efficient than RAII idioms.

If you don't need reference counting you can use scoped_ptr. But if you need it, you will have to pay for it, apart from how much you hide it.

Maybe your problem is allocating dinamically so many objects. If they are small ones, you will find really interesting the chapter 4 (Small-Object Allocation) of "Modern C++ Design" (Andrei Alexandrescu).

Answer 2

Most people tend to avoid garbage collectors in C++.

They are generally not necessary, once you learn to use RAII to manage your resources, and because C++ does not have proper support for garbage collection, the GC's that exist have a couple of problems:

• They don't catch every allocation (they have to make a conservative guess of whether some allocation is referenced or not)
• They may not play nice with destructors

Of course there are situations where a GC in C++ is useful. But 95% of the cases, you'll be better served simply by learning the appropriate memory management techniques (RAII) yourself.

But I haven't used Autozone, and don't know how well it works in your case or in general.

Answer 3

Actually, Garbage Collection was a part of the upcoming C++ 20XX standard, but was dropped for reasons of difficulty of implementation, complexity, etc...

So, sure, lots of people avoid GC in C++, but there is a strong enough demand that the standards committee is actively considering it.

Apple's AutoZone is a language agnostic garbage collector that could be bent for use with C++. Certainly, that AutoZone works for Objective-C (and C) would make for a good foundation implementation.

AutoZone is also used by the MacRuby project and, I believe, a handful of other projects. It is designed to be portable, though the implementation has bits specific to the x86 and ppc architectures -- you would need to port it to other CPU types, if necessary.

The collector has an API that can be used directly to register/unregister objects and express connectivity, etc...

It wouldn't be easy, but it is certainly doable.

Answer 4

No I haven't tried that. You may try this from hp labs, with more details going here . This collector works on Linux, *BSD, recent Windows versions, MacOS X, HP/UX, Solaris, Tru64, Irix and a few other operating systems.