Tufts Computer Engineer Wins National Award for Research

New software could help improve efficiency without sacrificing security

MEDFORD/SOMERVILLE, Mass. – Efforts to improve how computer programs manage memory without sacrificing security have earned Sam Guyer, an assistant professor of computer science in the Tufts University School of Engineering, an early career award from the National Science Foundation (NSF).

 With the $443,000, five-year NSF grant, Guyer will explore a new approach to improving virtual machines — complex pieces of software that manage computing resources such as memory.

 Modern managed computer programming languages, such as Java and C#, eliminate many errors and security risks that have plagued traditional languages such as C and C++. But this security comes at a price: programs written in managed languages are more expensive to run because they require more computing resources.  

 This creates a dilemma for programmers, Guyer notes. "They can use a safe and secure managed language that requires more memory and server resources or they can continue taking chances with languages such as C and C++."

 Recycling the garbage

 To solve this problem cost-effectively, Guyer wants to improve the virtual machine by strengthening the process of "garbage collection." The garbage collector identifies what regions of application data are no longer needed by the program. Then it deletes this data, freeing up vital space for later computations.

 But current garbage collection techniques have trouble identifying the trash. "The problem with existing techniques for garbage collection is that they don't know which parts of memory are likely to be garbage, so they have to look at it all," Guyer explains. "It takes a lot of work to identify unused memory — the more data the program has, the more work it takes."

 "If we knew just a little bit more about what the program's doing, we could probably do a lot better in recycling memory that's not being used, "he says."And that's where cooperation between programmer and machine comes in."

 In Guyer's approach, the programmer will identify the large-scale structures and patterns of use in the program. "If the garbage collector somehow knows that a block of data represents a particular user, then when the user logs off, it can collect that memory without looking at all the rest of the data," he says.

 For example, in an online banking session the server stores a chunk of memory that represents current information at the bank. When a user logs off, the information about that particular session no longer needs to be stored. Conversely, a program may contain a database that should remain permanent and not be discarded.

 Guyer's software will recognize what is to be saved and what should be discarded as garbage. "There are patterns," he says." We're developing different tools that will let us look inside the program and see those kinds of patterns."

 "The key idea is that with extra information, virtual machines can provide much more efficient services because they are customized to each application's needs," Guyer says.


Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate, and professional programs across the university's schools is widely encouraged.

About Tufts School of Engineering

Located on Tufts' Medford/Somerville campus, the School of Engineering offers a rigorous engineering education in a unique environment that blends the intellectual and technological resources of a world-class research university with the strengths of a top-ranked liberal arts college. Close partnerships with Tufts' excellent undergraduate, graduate and professional schools, coupled with a long tradition of collaboration, provide a strong platform for interdisciplinary education and scholarship. The School of Engineering’s mission is to educate engineers committed to the innovative and ethical application of science and technology in addressing the most pressing societal needs, to develop and nurture twenty-first century leadership qualities in its students, faculty, and alumni, and to create and disseminate transformational new knowledge and technologies that further the well-being and sustainability of society in such cross-cutting areas as human health, environmental sustainability, alternative energy, and the human-technology interface.


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