Re: C++ Memory Management Innovation: GC Allocator

From:
"Chris Thomasson" <cristom@comcast.net>
Newsgroups:
comp.lang.c++.moderated
Date:
Tue, 29 Apr 2008 17:43:31 CST
Message-ID:
<M6edna_pWva1DorVnZ2dnUVZ_smnnZ2d@comcast.com>
"xushiwei" <xushiweizh@gmail.com> wrote in message
news:937d3306-48cd-4907-a984-99bf16a253b0@w4g2000prd.googlegroups.com...

{ Please note that top-posting is discouraged in this group. -mod }

These days I spent a lot of time researching Boehm GC, Hoard/
HeapLayers/reaps, streamflow, dlmalloc, etc.

Yes, "GC Allocator" is a region allocator. It's no innovation.


Here is a very crude dynamic region allocator I did for C++:

http://groups.google.com/group/comp.lang.c++/browse_frm/thread/68bdc76f9792de1f

it allows calls to free, however it just ends up decrementing a counter.
When the count drops to zero, it resets the entire region offset. I need to
add a reset function to the public interface. That way, no explicit calls to
free are needed. You can do something like:

void foo(int count) {
  for (; count > 0; --count) {
    ::operator new((i + 1) * 16);
  }
}

int main() {
  int i;
  for (i = 1 ;; ++i) {
    foo(i % 1024);
    thread_reset(); // resets threads region allocator
  }
  return 0;
}

But:

This (ScopeAlloc) is not a normal region allocator. All ScopeAlloc
instances in the same thread share their freelist. This makes you can
define a lot of ScopeAlloc instances (depends your needs). You even
can define a ScopeAlloc instance for each allocation.


I am interested in increasing the granularity of region allocators. I need
to look at your source-code when I get some time.

[...]

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