Re: [ALACPP] C++ GC (was smart pointers in C)

[Christopher Smith <x@xxxxxxxx>]

On Wed, 2003-07-02 at 11:51, Arlo Belshee wrote:
> > Ah! It seems like you are intending to still use the standard heap
> > allocator. That will make it pretty hard for the mark/sweep allocator to
> > win. Half the fun mark/sweep is having heap allocs that are almost as fast
> > as stack allocs.
> 
> What I'd really prefer is to make the selection of allocator orthogonal to the
> selection of memory management strategy. It'd be nice if the boost shared ptr
> allowed you to easily specify an allocator as part of the type (you can use it
> with an allocator, using a factory method and its custom destructor facility).
> Then the final user could choose which one to use.

Unfortunately, allocation is tightly coupled with automatic memory
management, at least of high-performance implementations.

> Besides, they've sped up the default heap a lot over time - custom allocators
> don't necessarily beat it any more. See earlier discussion on Alexandrescu's
> small object allocator's performance vs MSVC 6.0's default heap.

It's true that custom allocators are frequently not a win, but there is
a whole ton of overhead in managing a manually-managed heap. The 1000
millisecond times for allocating a raw are clearly much worse than can
be achieved with a managed heap (typically they can allocate with just a
few instructions).

> If however, you know of a really high performance allocator, it might be nice
> to provide that as an option one for the gc pointer.

I hear Java has a nice one. The CLR's is supposed to be pretty nice too.
;-)

--Chris
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