Understanding and debugging concurrent programs through visualisation

In this thesis, the development and evaluation of a visualisation system intended to support students in understanding and debugging concurrent programs is presented. The first phase of development consisted of examining how students understand and develop concurrent programs through phenomenographic research. The resulting outcome spaces included the students' understandings of tuple spaces, the purpose of a programming assignment and what developing, debugging and testing a concurrent program involves. The outcome spaces included categories ranging from simple understandings containing only what is necessary to complete the assignments to understandings that placed the program in a larger context beyond the assignment. These outcome spaces were used in a classification of defects in students' concurrent programs. The defects found in the students' programs were classified by the underlying human error and by the type of program failure the defect causes. This analysis of defects was used to determine appropriate measures to support students in avoiding such defects. Many of the students' defects were related to misunderstanding the goals of the assignment, so they were rewritten to clarify the goals. To give the students a more concrete demonstration of the situations their programs had to deal with, test packages were provided to them. Many of the students' defects were related to incorrect use of concurrency. To help students understand and correct these defects and learn from their mistakes, the visualisation system Atropos was developed. Atropos is intended to help students understand concurrent program behaviour in Java. Atropos supports backward debugging of concurrent Java programs through interactive exploration of a dynamic dependence graph. A solution for replay and dynamic dependence analysis of concurrent Java programs that may include data races was devised. Atropos was evaluated through a mixed-methods analysis of the behaviour of pairs of students using Atropos to debug concurrent programs. The results include a description of the ways in which students successfully made use of Atropos and suggestions for how it could be improved to better support their debugging approaches. While students appear to understand the dependence graph representation and how to apply it in debugging, they need more support from Atropos for eliding the implementation of data structures in order to examine their use.

Department dc:contributor.department

Tietotekniikan laitos

Grantor dc:publisher

Aalto University

Year dc:date.issued

2012

Author dc:creator

• Lönnberg, Jan

Advisors dc:contributor.advisor

• Ben-Ari, Mordechai, Associate Professor
• Malmi, Lauri, Professor

Contributors dc:contributor

• Aalto-yliopisto
• Aalto University

Language dc:language.iso

en

Repository record dc:identifier.uri

https://aaltodoc.aalto.fi/handle/123456789/5149

OAI record oai:identifier

https://aaltodoc.aalto.fi/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Aaaltodoc.aalto.fi%3A123456789%2F5149