ICSE 2015

This post originally appeared on the Software Carpentry website.

Back when I was still trying to do science myself, my field of study was software engineering. The International Conference on Software Engineering is the big gathering for researchers in that area, and this year's has just wrapped up. Thanks to this Gist from Mike Hoye, I was able to browse the papers presented at ICSE and co-located workshops (like him, I'm outside the Great Paywall of Academia), and I've included titles and abstracts below from the ones I think readers of this blog might enjoy. They're only a fraction of what was presented, and I freely admit the sample is biased toward the things I understand and find interesting, but I hope they'll convince you that people are doing solid empirical studies in software engineering, and producing insights that we can and should act on.

Note: just over half of these papers (13 of 24) had an easily-findable version online. I'm not going to do the experiment, but I confidently predict that those 13 will be more widely read, and more influential, than the other 11.

Lavallée and Robillard: Why Good Developers Write Bad Code: An Observational Case Study of the Impacts of Organizational Factors on Software Quality

How can organizational factors such as structure and culture have an impact on the working conditions of developers? This study is based on ten months of observation of an in-house software development project within a large telecommunications company. The observation was conducted during mandatory weekly status meetings, where technical and managerial issues were raised and discussed. Preliminary results show that many decisions made under the pressure of certain organizational factors negatively affected software quality. This paper describes cases depicting the complexity of organizational factors and reports on ten issues that have had a negative impact on quality, followed by suggested avenues for corrective action.

Chowdhury and Hindle: Mining StackOverflow to Filter out Off-topic IRC Discussion

Internet Relay Chat (IRC) is a commonly used tool by OpenSource developers. Developers use IRC channels to discuss programming related problems, but much of the discussion is irrelevant and off-topic. Essentially if we treat IRC discussions like email messages, and apply spam filtering, we can try to filter out the spam (the off-topic discussions) from the ham (the programming discussions). Yet we need labelled data that unfortunately takes time to curate.

To avoid costly curration in order to filter out off-topic discussions, we need positive and negative data-sources. On- line discussion forums, such as StackOverflow, are very effective for solving programming problems. By engaging in open-data, StackOverflow data becomes a powerful source of labelled text regarding programming. This work shows that we can train classifiers using StackOverflow posts as positive examples of on-topic programming discussion. YouTube video comments, notorious for their lack of quality, serve as training set of off- topic discussion. By exploiting these datasets, accurate classifiers can be built, tested and evaluated that require very little effort for end-users to deploy and exploit.

Labuschagne and Holmes: Do Onboarding Programs Work?

Open source software systems rely on community source code contributions to fix bugs and develop new features. Unfortunately, it is often difficult to become an effective contributor on open-source projects due to the complexity of the tools required to develop and test new patches and the challenge of breaking into an already-formed social organization. To help new contributors learn their development practices, OSS projects have created onboarding programs that, for example, identify easy 'first bugs' and mentor new developers' contributions. However, we found that developers who join an organization through these programs are half as likely to transition into long-term community members than developers who do not use these programs. Measuring the impact of these programs is important, as coordinating and staffing onboarding projects is expensive. This paper examines onboarding programs employed by Mozilla and demonstrates that they are not as effective at transitioning new developers into long-term contributors as might be hoped, although developers who do succeed through these programs find them valuable.

Bosu, Greiler, and Bird: Characteristics of Useful Code Reviews: An Empirical Study at Microsoft

Over the past decade, both open source and commercial software projects have adopted contemporary peer code review practices as a quality control mechanism. Prior research has shown that developers spend a large amount of time and effort performing code reviews. Therefore, identifying factors that lead to useful code reviews can benefit projects by increasing code review effectiveness and quality. In a three-stage mixed research study, we qualitatively investigated what aspects of code reviews make them useful to developers, used our findings to build and verify a classification model that can distinguish between useful and not useful code review feedback, and finally we used this classifier to classify review comments enabling us to empirically investigate factors that lead to more effective code review feedback.

In total, we analyzed 1.5 millions review comments from five Microsoft projects and uncovered many factors that affect the usefulness of review feedback. For example, we found that the proportion of useful comments made by a reviewer increases dramatically in the first year that he or she is at Microsoft but tends to plateau afterwards. In contrast, we found that the more files that are in a change, the lower the proportion of comments in the code review that will be of value to the author of the change. Based on our findings, we provide recommendations for practitioners to improve effectiveness of code reviews.

Jbara and Feitelson: How Programmers Read Regular Code: A Controlled Experiment Using Eye Tracking

Regular code, which includes repetitions of the same basic pattern, has been shown to have an effect on code comprehension: a regular function can be just as easy to comprehend as an irregular one with the same functionality, despite being longer and including more control constructs. It has been speculated that this effect is due to leveraging the understanding of the first instances to ease the understanding of repeated instances of the pattern. To verify and quantify this effect, we use eye tracking to measure the time and effort spent reading and understanding regular code. The results are that time and effort invested in the initial code segments are indeed much larger than those spent on the later ones, and the decay in effort can be modeled by an exponential or cubic model. This shows that syntactic code complexity metrics (such as LOC and MCC) need to be made context-sensitive, e.g. by giving reduced weight to repeated segments according to their place in the sequence.

Beller, Zaidman, and Karpov: The Last Line Effect

Micro-clones are tiny duplicated pieces of code; they typically comprise only a few statements or lines. In this paper, we expose the "last line effect," the phenomenon that the last line or statement in a micro-clone is much more likely to contain an error than the previous lines or statements. We do this by analyzing 208 open source projects and reporting on 202 faulty micro-clones.

From the body of the paper: In total, our findings confirm the presence of a strong last line and last statement effect, accepting both RQ1 and RQ2. We assume the effect to be caused by and large through copy- and-pasting code, and that developers have a psychological tendency to think changes of similar code blocks are finished earlier than they really are. This way, they miss one critical last modification.

Martin, Cordy, Adams, and Antoniol: Make It Simple – An Empirical Analysis of GNU Make Feature Use in Open Source Projects

Make is one of the oldest build technologies and is still widely used today, whether by manually writing Makefiles, or by generating them using tools like Autotools and CMake. Despite its conceptual simplicity, modern Make implementations such as GNU Make have become very complex languages, featuring functions, macros, lazy variable assignments and (in GNU Make 4.0) the Guile embedded scripting language. Since we are interested in understanding how widespread such complex language features are, this paper studies the use of Make features in almost 20,000 Makefiles, comprised of over 8.4 million lines, from more than 350 different open source projects. We look at the popularity of features and the difference between hand-written Makefiles and those generated using various tools. We find that generated Makefiles use only a core set of features and that more advanced features (such as function calls) are used very little, and almost exclusively in hand-written Makefiles.

MacLeod, Storey, and Bergen: Code, Camera, Action: How Software Developers Document and Share Program Knowledge Using YouTube

Creating documentation is a challenging task in software engineering and most techniques involve the laborious and sometimes tedious job of writing text. This paper explores an alternative to traditional text-based documentation, the screencast, which captures a developer's screen while they narrate how a program or software tool works. We conducted a study to investigate how developers produce and share developer-focused screencasts using the YouTube social platform. First, we identified and analyzed a set of development screencasts to determine how developers have adapted to the medium to meet the demands of development-related documentation needs. We also explored the techniques and strategies used for sharing software knowledge. Second, we interviewed screencast producers to understand their motivations for creating screencasts, and to uncover the perceived benefits and challenges in producing code-focused videos. Our findings reveal that video is a useful medium for communicating program knowledge between developers, and that developers build their online personas and reputation by sharing videos through social channels.

See this link for the first author's MSc thesis.

Lubick, Barik, and Murphy-Hill: Can Social Screencasting Help Developers Learn New Tools?

An effective way to learn about software development tools is by directly observing peers' workflows. However, these tool knowledge transfer events happen infrequently because developers must be both colocated and available. We explore an online social screencasting system that removes the dependencies of colocation and availability while maintaining the beneficial tool knowledge transfer of peer observation . Our results from a formative study indicate these online observations happen more frequently than in-person observations, but their effects are only temporary. We conclude that while peer observation facilitates online knowledge transfer, it is not the only component – other social factors may be involved.

Agrawal, Amreen, and Mockus: Commit Quality in Five High Performance Computing Projects

High Performance Computing (HPC) has a long history of software development but relatively little is known about the approaches this community uses to create and maintain software. To close this gap we study the practices of using version control tools in five HPC production projects. We also contrast these practices to practices used in three distinct non-HPC open source projects. We first obtain version history of the projects from SVN, Mercurial, and Git. We then clean and process the data and use published material to construct three measures of code commit quality: the fraction of unique commit comments, their size, and the number of files per commit. Our results indicate relatively high but declining commit quality, and relatively large commits in HPC projects. We expect this work to highlight the differences among different software engineering domains and may lead to ideas suggesting good practices of using software tools in these domains.

Wang, Janjusic, Iversen, Thornton, Karssovski, Wu, and Xu: A Scientific Function Test Framework for Modular Environmental Model Development: Application to the Community Land Model

As environmental models have become more complicated, we need new tools to analyze and validate these models and to facilitate collaboration among field scientists, observation dataset providers, environmental system modelers, and computer scientists. Modular design and function test of environmental models have gained attention recently within the Biological and Environmental Research Program of the U.S. Department of Energy. In this paper, we will present our methods and software tools 1) to analyze environmental software and 2) to generate modules for scientific function testing of environmental models. We have applied these methods to the Community Land Model with three typical scenarios: 1) benchmark case function validation, 2) observation- constraint function validation, and 3) a virtual root module generation for root function investigation and evaluation. We believe that our strategies and experience in scientific function test framework can be beneficial to many other research programs that adapt integrated environmental modeling methodology.

Hata, Todo, Onoue, and Matsumoto: Characteristics of Sustainable OSS Projects: A Theoretical and Empirical Study

How can we attract developers? What can we do to incentivize developers to write code? We started the study by introducing the population pyramid visualization to software development communities, called software population pyramids, and found a typical pattern in shapes. This pattern comes from the differences in attracting coding contributors and discussion contributors. To understand the causes of the differences, we then build game-theoretical models of the contribution situation. Based on these results, we again analyzed the projects empirically to support the outcome of the models, and found empirical evidence. The answers to the initial questions are clear. To incentivize developers to code, the projects should prepare documents, or the projects or third parties should hire developers, and these are what sustainable projects in GitHub did in reality. In addition, making innovations to reduce the writing costs can also have an impact in attracting coding contributors.

Kanij, Merkel, and Grundy: An Empirical Investigation of Personality Traits of Software Testers

Software testing is the process of an execution-based investigation of some aspects of the software's quality. The efficiency of the process depends on the methods and technologies used, but crucially also on the human testers. Software testers typically attempt to anticipate and expose ways software may be defective, a fundamentally different task set to those of other software development practitioners. This raises the question of whether the personality of software testers may be different to other people involved in software development. To test this hypothesis, we collected personality profiles using the big five factor model of around 200 software development practitioners. Analysis of this data indicates that software testers are significantly higher on the conscientiousness factor than other software development practitioners, while other factors remain broadly consistent.

Szabo: Novice Code Understanding Strategies During a Software Maintenance Assignment

Existing efforts on teaching software maintenance have focussed on constructing adequate codebases that students with limited knowledge could maintain, with little focus on the learning outcomes of such exercises and of the approaches that students employ while performing maintenance. An analysis of the code understanding strategies employed by novice students as they perform software maintenance exercises is fundamental for the effective teaching of software maintenance. In this paper, we analyze the strategies employed by second year students in a maintenance exercise over a large codebase. We analyze student reflections on their code understanding, maintenance process and the use of tools. We show that students are generally capable of working with large codebases. Our study also finds that the majority of students follow a systematic approach to code understanding, but that their approach can be significantly improved through the use of tools and a better understanding of reverse engineering approaches.

Falkner, Szabo, Vivian, and Falkner: Evolution of Software Development Strategies

The development of discipline-specific cognitive and meta-cognitive skills is fundamental to the successful mastery of software development skills and processes. This development happens over time and is influenced by many factors, however its understanding by teachers is crucial in order to develop activities and materials to transform students from novice to expert software engineers. In this paper, we analyse the evolution of learning strategies of novice, first year students, to expert, final year students. We analyse reflections on software development processes from students in an introductory software development course, and compare them to those of final year students, in a distributed systems development course. Our study shows that computer science - specific strategies evolve as expected, with the majority of final year students including design before coding in their software development process, but that several areas still require scaffolding activities to assist in learning development.

Czerwonka, Greiler, and Tilford: Code Reviews Do Not Find BugsHow the Current Code Review Best Practice Slows Us Down

Because of its many uses and benefits, code reviews are a standard part of the modern software engineering workflow. Since they require involvement of people, code reviewing is often the longest part of the code integration activities. Using experience gained at Microsoft and with support of data, we posit (1) that code reviews often do not find functionality issues that should block a code submission; (2) that effective code reviews should be performed by people with specific set of skills; and (3)that the social aspect of code reviews cannot be ignored. We find that we need to be more sophisticated with our guidelines for the code review workflow. We show how our findings from code reviewing practice influence our code review tools at Microsoft. Finally,we assert that, due to its costs, code reviewing practice is a topic deserving to be better understood, systematized and applied to software engineering workflow with more precision than the best practice currently prescribes.

Zhou, Lou, Zhang, Lin, Lin, and Qin: An Empirical Study on Quality Issues of Production Big Data Platform

Big Data computing platform has evolved to be a multi-tenant service. The service quality matters because system failure or performance slowdown could adversely affect business and user experience. To date, there is few study in literature on service quality issues of production Big Data computing platform. In this paper, we present an empirical study on the service quality issues of Microsoft ProductA, which is a company-wide multi-tenant Big Data computing platform, serving thousands of customers from hundreds of teams. ProductA has a well-defined escalation process (i.e., incident management process), which helps customers report service quality issues on 24/7 basis. This paper investigates the common symptom, causes and mitigation of service quality issues in Big Data platform. We conduct a comprehensive empirical study on 210 real service quality issues of ProductA. Our major findings include (1) 21.0% of escalations are caused by hardware faults; (2) 36.2% are caused by system side defects; (3) 37.2% are due to customer side faults. We also studied the general diagnosis process and the commonly adopted mitigation solutions. Our study results provide valuable guidance on improving existing development and maintenance practice of production Big Data platform, and motivate tool support.

Hermans and Murphy-Hill: Enron's Spreadsheets and Related Emails: A Dataset and Analysis

Spreadsheets are used extensively in business processes around the world and as such, are a topic of research interest. Over the past few years, many spreadsheet studies have been performed on the EUSES spreadsheet corpus. While this corpus has served the spreadsheet community well, the spreadsheets it contains are mainly gathered with search engines and might therefore not represent spreadsheets used in companies. This paper presents an analysis of a new dataset, extracted from the Enron email archive, containing over 15,000 spreadsheets used within the Enron Corporation. In addition to the spreadsheets, we also present an analysis of the associated emails, where we look into spreadsheet-specific email behavior.

Our analysis shows that 1) 24% of Enron spreadsheets with at least one formula contain an Excel error, 2) there is little diversity in the functions used in spreadsheets: 76% of spreadsheets in the presented corpus use the same 15 functions and, 3) the spreadsheets are substantially more smelly than the EUSES corpus, especially in terms of long calculation chains. Regarding the emails, we observe that spreadsheets 1) are a frequent topic of email conversation with 10% of emails either referring to or sending spreadsheets and 2) the emails are frequently discussing errors in and updates to spreadsheets.

Note: while some people are already citing this as "proof" that spreadsheets are bad, the more interesting question is whether they are worse: is the error rate of (for example) R programs written by people with the same formal training in data analysis skills higher, lower, or the same? As far as I know, that study has yet to be done...

Nanz and Furia: A Comparative Study of Programming Languages in Rosetta Code

Sometimes debates on programming languages are more religious than scientific. Questions about which language is more succinct or efficient, or makes developers more productive are discussed with fervor, and their answers are too often based on anecdotes and unsubstantiated beliefs. In this study, we use the largely untapped research potential of Rosetta Code, a code repository of solutions to common programming tasks in various languages, which offers a large data set for analysis. Our study is based on 7,087 solution programs corresponding to 745 tasks in 8 widely used languages representing the major programming paradigms (procedural: C and Go; object-oriented: C# and Java; functional: F# and Haskell; scripting: Python and Ruby). Our statistical analysis reveals, most notably, that: functional and scripting languages are more concise than procedural and object- oriented languages; C is hard to beat when it comes to raw speed on large inputs, but performance differences over inputs of moderate size are less pronounced and allow even interpreted languages to be competitive; compiled strongly-typed languages, where more defects can be caught at compile time, are less prone to runtime failures than interpreted or weakly-typed languages. We discuss implications of these results for developers, language designers, and educators.

Casalnuovo, Devanbu, Oliveira, Filkov, and Ray: Assert Use in GitHub Projects

Asserts have long been a strongly recommended (if non-functional) adjunct to programs. They certainly don't add any user-evident feature value; and it can take quite some skill and effort to devise and add useful asserts. However, they are believed to add considerable value to the developer. Certainly, they can help with automated verification; but even in the absence of that, claimed advantages include improved understandability, maintainability, easier fault localization and diagnosis, all eventually leading to better software quality. We focus on this latter claim, and use a large dataset of asserts in C and C++ programs to explore the connection between asserts and defect occurrence. Our data suggests a connection: functions with asserts do have significantly fewer defects. This indicates that asserts do play an important role in software quality; we therefore explored further the factors that play a role in assertion placement: specifically, process factors (such as developer experience and ownership) and product factors , particularly interprocedural factors, exploring how the placement of assertions in functions are influenced by local and global network properties of the callgraph. Finally, we also conduct a differential analysis of assertion use across different application domains.

Salman, Misirli, and Juristo: Are Students Representatives of Professionals in Software Engineering Experiments?

Most of the experiments in software engineering employ students as subjects. This raises concerns about the realism of the results acquired through students and adaptability of the results to software industry. Aim: We compare students and professionals to understand how well students represent professionals as experimental subjects in SE research. Method: The comparison was made in the context of two test-driven development experiments conducted with students in an academic setting and with professionals in a software organization. We measured the code quality of several tasks implemented by both subject groups and checked whether students and professionals perform similarly in terms of code quality metrics. Results: Except for minor differences, neither of the subject groups is better than the other. Professionals produce larger, yet less complex, methods when they use their traditional development approach, whereas both subject groups perform similarly when they apply a new approach for the first time. Conclusion: Given a carefully scoped experiment on a development approach that is new to both students and professionals, similar performances are observed. Further investigation is necessary to analyze the effects of subject demographics and level of experience on the results of SE experiments.

Tufano, Palomba, Bavota, Oliveto, Di Penta, De Lucia, and Poshyvanyk: When and Why Your Code Starts to Smell Bad

In past and recent years, the issues related to managing technical debt received significant attention by researchers from both industry and academia. There are several factors that contribute to technical debt. One of these is represented by code bad smells, i.e., symptoms of poor design and implementation choices. While the repercussions of smells on code quality have been empirically assessed, there is still only anecdotal evidence on when and why bad smells are introduced. To fill this gap, we conducted a large empirical study over the change history of 200 open source projects from different software ecosystems and investigated when bad smells are introduced by developers, and the circumstances and reasons behind their introduction. Our study required the development of a strategy to identify smell-introducing commits, the mining of over 0.5M commits, and the manual analysis of 9,164 of them (i.e., those identified as smell-introducing). Our findings mostly contradict common wisdom stating that smells are being introduced during evolutionary tasks. In the light of our results, we also call for the need to develop a new generation of recommendation systems aimed at properly planning smell refactoring activities.

Smith, Bird, and Zimmermann: Build It Yourself! Homegrown Tools in a Large Software Company

Developers sometimes take the initiative to build tools to solve problems they face. What motivates developers to build these tools? What is the value for a company? Are the tools built useful for anyone besides their creator? We conducted a qualitative study of toolbuilding, adoption, and impact within Microsoft. This paper presents our findings on the extrinsic and intrinsic factors linked to toolbuilding, the value of building tools, and the factors associated with tool spread. We find that the majority of developers build tools. While most tools never spread beyond their creator's team, most have more than one user, and many have more than one collaborator. Organizational cultures that are receptive towards toolbuilding produce more tools, and more collaboration on tools. When nurtured and spread, homegrown tools have the potential to create significant impact on organizations.

Gousios, Zaidman, Storey, and van Deursen: Work Practices and Challenges in Pull-Based Development: The Integrator's Perspective

In the pull-based development model, the integrator has the crucial role of managing and integrating contributions. This work focuses on the role of the integrator and investigates working habits and challenges alike. We set up an exploratory qualitative study involving a large-scale survey of 749 integrators, to which we add quantitative data from the integrator's project. Our results provide insights into the factors they consider in their decision making process to accept or reject a contribution. Our key findings are that integrators struggle to maintain the quality of their projects and have difficulties with prioritizing contributions that are to be merged. Our insights have implications for practitioners who wish to use or improve their pull-based development process, as well as for researchers striving to understand the theoretical implications of the pull-based model in software development.

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