[Colloq] PhD Thesis Proposal - FRIDAY, AUG. 25 - Fabio Rojas

Rachel Kalweit rachelb at ccs.neu.edu
Wed Aug 23 11:09:39 EDT 2006


College of Computer and Information Science
presents
PhD Thesis Proposal:
Fabio Rojas

Title: Predicting Garbage Collection Behavior Using Object Lifetime Models

Friday, August 25, 2006
12:00pm
366 West Village H

Abstract:
Garbage Collection is a technology for automatically reclaiming 
dynamically allocated heap storage that is no longer needed by a 
program. Garbage collection removes the burden of deallocating memory 
from the programmer, removing a common source of programming errors, and 
it allows for better interoperability between third party libraries.

There are several different garbage collection strategies, each with its 
own advantages and disadvantages. Different strategies will collect 
different regions of the heap, or treat newly allocated objects 
differently. These decisions will impact the overall performance of the 
garbage collected application, making the choice of garbage collection 
strategy an important part of performance tuning. The objects allocated 
by an application will exhibit different lifetime behavior than those 
allocated by another application. This is one of the reasons why no one 
garbage collection strategy is always best for all possible programs. It 
is important to understand how different collection techniques will 
affect the performance of an application. It is also desirable to be 
able to predict how garbage collection will impact the runtime 
performance of an application.

Object behavior is complex and difficult to understand. But it is 
possible to build mathematical models of object lifetimes which 
approximate the behaviors of an application's objects. While these 
models cannot capture all of the details of object behavior, they have 
been shown to be a useful tool in analyzing garbage collection 
performance. Until now building these models has been a computationally 
expensive task that must be performed offline.

The goal of my research is to use object lifetime models to predict the 
impact that different garbage collection techniques would have on the 
performance of an application at runtime. My approach will be to build a 
system that gathers the information needed to model the behavior of a 
running application with minimal impact on the application itself.  The 
model will then be used to estimate the impact of several different 
garbage collection strategies on the application. The system will use 
these estimates to choose the best collection algorithm from those 
available at runtime.

Advisor: Will Clinger




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