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Event Entry

What and Who

Expositor: Scriptable Time-Travel Debugging with First Class Traces

Prof. Michael Hicks
University of Maryland
SWS Distinguished Lecture Series

Michael Hicks is an associate professor in the Computer Science Department and UMIACS at the University of Maryland, College Park. His primary research interest is to develop and evaluate techniques to improve software reliability and security. Michael is the Director of the Maryland Cybersecurtiy Center (MC2), and with Jeff Foster he directs PLUM, the lab for Programming Languages research at the University of Maryland.

Michael received his Ph.D. in Computer and Information Science from the University of Pennsylvania in August 2001, and he spent one year as a post-doctoral associate affiliated with the Information Assurance Institute of the Computer Science Department at Cornell University. During academic 2008 - 2009, he was on sabbatical in Cambridge, England. From September to November he was at Microsoft Research and from December to August 2009 he was at the University of Cambridge Computer Laboratory.

AG 1, AG 2, AG 3, AG 4, AG 5, SWS, RG1, MMCI  
AG Audience

Date, Time and Location

Friday, 30 November 2012
90 Minutes
E1 5


We present Expositor, a new debugging environment that combines scripting and time-travel debugging to allow developers to automate complex debugging tasks. The fundamental abstraction provided by Expositor is the execution trace, which is a time-indexed sequence of program state snapshots. Developers can manipulate traces as if they were simple lists with operations such as map and filter. Under the hood, Expositor efficiently implements traces as lazy, sparse interval trees, whose contents are materialized on demand. Expositor also provides a novel data structure, the edit hash array mapped trie, which is a lazy implementation of sets, maps, multisets, and multimaps that enables developers to maximize the efficiency of their debugging scripts. We have used Expositor to debug a stack overflow and to unravel a subtle data race in Firefox. We believe that Expositor represents an important step forward in improving the technology for diagnosing complex, hard-to-understand bugs.
This is joint work with Yit Phang Khoo and Jeff Foster, both at Maryland


Susanne Rock
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Susanne Rock, 11/13/2012 11:40 -- Created document.