Automated Software Debugging Using Hybrid Static/Dynamic Analysis

With the increasing complexity of today's software, the software development process is becoming highly time and resource consuming. The increasing number of software configurations, input parameters, usage scenarios, supporting platforms, external dependencies, and versions plays an important role in expanding the costs of maintaining and repairing unforeseeable software faults. To repair software faults, developers spend considerable time in identifying the scenarios leading to those faults and root-causing the problems. While software debugging remains largely manual, it is not the case with software testing and verification. The goal of this research is to improve the software development process in general, and software debugging process in particular, by devising techniques and methods for automated software debugging, which leverage the advances in automatic test case generation and replay. In this research, novel algorithms are devised to discover faulty execution paths in programs by utilizing already existing software test cases, which can be either automatically or manually generated. The execution traces, or alternatively, the sequence covers of the failing test cases are extracted. Afterwards, commonalities between these test case sequence covers are extracted, processed, analyzed, and then presented to the developers in the form of subsequences that may be causing the fault. The hypothesis is that code sequences that are shared between a number of faulty test cases for the same reason resemble the faulty execution path, and hence, the search space for the faulty execution path can be narrowed down by using a large number of test cases. To achieve this goal, an efficient algorithm is implemented for finding common subsequences among a set of code sequence covers. Optimization techniques are devised to generate shorter and more logical sequence covers, and to select subsequences with high likelihood of containing the root cause among the set of all possible common subsequences. A hybrid static/dynamic analysis approach is designed to trace back the common subsequences from the end to the root cause. A debugging tool is created to enable developers to use the approach, and integrate it with an existing Integrated Development Environment. The tool is also integrated with the environment's program editors so that developers can benefit from both the tool suggestions, and their source code counterparts. Finally, a comparison between the developed approach and the state-of-the-art techniques shows that developers need only to inspect a small number of lines in order to find the root cause of the fault. Furthermore, experimental evaluation shows that the algorithm optimizations lead to better results in terms of both the algorithm running time and the output subsequence length.

Archaeological Testing at the John Brice II (Jennings-Brice) House, 18AP53, 195 Prince George Street, Annapolis, Maryland

In the fall of 1989, emergency excavation was undertaken in conjunction with restoration work at the John Brice II (Jennings-Brice) House, 18AP53. The exact date of construction for this brick home is problematic, and it was hoped that archaeological investigation could provide conclusive evidence to firmly establish the structure's date of construction. Excavation of one 5 X 5 ft. unit revealed the presence of 10 separate soil layers and four features of note, described in detail below. Unfortunately, no builders trench or similar feature by which we might date the house's construction was recovered. Future plans and possibilities for excavation at the property are outlined with the hopes of performing subsequent work at this rich site. We anticipate a focus on the arrangement and changes in use of the houselot, amassing evidence to support the presence of a vernacular garden on the property during the 18th century, as well as researching refuse disposal patterns, and clues to changing lifeways through the 18th century.

Archaeological Testing at 10 Francis Street, Annapolis, Maryland, 18AP55

In August 1990, archaeological investigations were permitted at 10 Francis Street (18AP55). The house on this property dates to the early eighteenth century and the property has had little disturbance since that time. Excavation here has provided an excellent opportunity to learn more about this period of Annapolis' history. Two units were excavated and are described fully within this report. One unit, placed next to the house foundation, revealed an eighteenth-century brick sidewalk beneath the current mid-nineteenth-century brick sidewalk, but it did not contain any builder's trench for the structure. A second unit, randomly place in the back yard, revealed intact stratigraphy dating back to the early eighteenth century. These findings demonstrate the integrity of this site and its potential for future investigation. Any alterations to this property should proceed only after further controlled excavations have taken place.