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BACTAC - Hirzel

ECOT 831

Effectiveness of Garbage Collection and Explicit Deallocation
Grad Student, Computer Science

Garbage collection is the automatic reclamation of heap storage. When an object is not reachable through pointers anymore, it is declared "dead" and its memory is reclaimed. In C, you do not know exactly which values are pointers and which are not. Therefore, the garbage collector must be conservative, it must not reclaim an object if anything that looks like a pointer seems to point to it. Other than in Java or Lisp, in C explicit deallocation (via free()) is more common than the use of garbage collectors.

For our experiments, we use the Boehm/Demers/Weiser conservative garbage collector for C. We compare how much memory it reclaims to how much the explicit deallocation inserted by the programmer reclaims. We also provide the garbage collector with more accurate pointer/non-pointer information and see how much this improves its effectiveness. In most of our benchmarks, the accuracy makes no difference. For those where it does, we investigate for which memory area (stack, heap, or global) accurate information is helpful.

BACTAC, the Beverage And Chips Tuesday Afternoon Colloquium, is a weekly forum run by graduate students. The goal is provide an informal setting in which anyone can (basically) present anything. In the past, we have had practice talks for conferences and job interviews, research reports, juggle lessons (!), student representative reports, internship discussions, an introduction to ergonomics, and "pay attention to this when you are going to look for job" discussions.

BACTAC is meant to be an informal and social event to promote the interaction among graduate students. BACTAC is typically held every Tuesday, at 3:30pm, in room ECOT 831. Free munchies and drinks are provided.

Please email Caleb Phillips for more information or if you want to be a speaker.

See also:
Department of Computer Science
College of Engineering and Applied Science
University of Colorado Boulder
Boulder, CO 80309-0430 USA
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May 5, 2012 (13:44)