Comment-based Concept Location over System Dependency Graphs

Abstract Software maintenance is one of the most expensive phases of software development and understanding a program is one of the most important tasks of software maintenance. Before making the change to the program, software engineers need to find the location, or locations, where the changes will be made, they need to understand the program. Real applications are huge, sometimes old, were written by other person and it is difficult to find the location of the instructions related to a specific problem domain concept. There are various techniques to find these locations minimizing the time spent, but this stage of software development continues to be one of the most expensive and longer. The concept location is a crucial task for program understanding. This paper presents a project whose main objective is to explore and combine two Program Comprehension techniques: visualization of the system dependency graph and concept location over source code comments. The idea is to merge both features in order to perform concept location in system dependency graphs. More than locate a set of hot instructions (based on the associated comments) it will allow to detect the other instructions (the whole method). ACM Subject Classification D.2.7 Maintenanc

Identifying Defects Related to the Order in which Messages are Received in Message-Passing Systems

Improving the quality of software artifacts and products is an essential activity for everyone working on the development of software. Testing is one approach to reveal defects and faults in software. In recent years, message-passing systems have grown to a significant degree due to the rise of distributed systems, embedded systems, and so forth. In message-passing systems, components communicate with each other through sending and receiving messages. This message-passing mechanism introduces new opportunities for testing programs due to the fact that the time a message is delivered is not guaranteed, so the order in which messages are delivered is also not guaranteed. This non-determinism introduces interleaving and parallelization and subsequently a new source of software defects like race conditions. In this thesis, we have explained a new approach to testing a given component for identifying software faults related to the order in which messages are received by that component. We reorder messages coming to a certain component and deliver them in a different distinct ordering each time. We have three different methods for achieving message reordering: Blocking, Buffering, and Adaptive Buffering. We evaluate the effectiveness of our new testing methods using four metrics: Ordering Coverage, Coverage Rate, Slowdown Overhead, and Memory Overhead. We have implemented our Reordering Framework on QNX Neutrino 6.5.0 and compared our reordering methods with each other and with the naive random case using our experiments. We have also showed that our testing approach applies to real programs and can reveal real bugs in software