either me or GC sux badly (GC don't reuse free memory)

[ketmar via Digitalmars-d]

Hello.

let's run this program:

  import core.sys.posix.unistd;
  import std.stdio;
  import core.memory;

  void main () {
    uint size = 1024*1024*300;
    for (;;) {
      auto buf = new ubyte[](size);
      writefln("%s", size);
      sleep(1);
      size += 1024*1024*100;
      buf = null;
      GC.collect();
      GC.minimize();
    }
  }

pretty innocent, right? i even trying to help GC here. but...

  314572800
  419430400
  524288000
  629145600
  734003200
  core.exception.OutOfMemoryError@(0)

oooops.

by the way, this is not actually "no more memory", this is "i'm out of
address space" (yes, i'm on 32-bit system, GNU/Linux).

the question is: am i doing something wrong here? how can i force GC to
stop eating my address space and reuse what it already has?

sure, i can use libc malloc(), refcounting, and so on, but the question
remains: why GC not reusing already allocated and freed memory?

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