Bug localization via searching crowd-contributed code

FineLocator: A novel approach to method-level fine-grained bug localization by query expansion

To improve the software debugging efficiency, bug localization techniques have been developed to automatically locate buggy files based on bug reports. Traditional information retrieval-based bug localization cannot deal with the lexical mismatch, thus its performance is limited. In recent years, some deep learning models have been proposed to learn the semantics of bug reports and source files to bridge the lexical gap. However, their accuracy is still limited as building accurate semantic representations of bug reports and source files is very challenging. Recently, relevance matching was proposed to identify whether a document is relevant to a given query by considering both local matching and global matching. In this work, we propose a novel framework DreamLoc, which utilizes a relevance matching model to locate buggy files. Specifically, DreamLoc conducts the local matching by employing an attention-based mechanism to calculate the matching scores between bug report terms and code snippets. It also conducts the global matching by employing a gating mechanism to aggregate results of local matching and obtain the final matching score between a bug report and a source file. Since the local matching considers the relevance between each word and the global matching differentiates the importance of words, DreamLoc can effectively model the characteristics of bug reports and source files. Experimental results on five benchmark datasets show that DreamLoc outperforms five state-of-the-art models. For example, compared with DeepLoc, a recently proposed approach, the evaluation measures Accuracy@10, MAP, and MRR are improved by 6.4%, 7.4%, and 7.2%, respectively.

Software bugs remain frequent in the life cycle of software development and maintenance. Automatic localization of buggy source code files is critical for timely bug fixing and improving the efficiency of software quality assurance. Various bug localization techniques have been proposed using different dimensions of features. Recent studies have shown that different dimensions of features may play different roles in bug localization. Unfortunately, how to effectively merge these dimensions of features for improving bug localization has rarely been investigated. This article presents a Multi-Dimension Convolutional Neural Network (MD-CNN) model for bug localization automatically based on a bug report. Our approach has dual-novelty. First, we identify and extract five statistical dimensions of features. Second, we design a Convolutional Neural Network (CNN) model that takes our five statistical dimensions of features as the input and iteratively learns the complex and non-linear relationship between the features and the bug locations. The MD-CNN bug localization model is verified using six large-scale open source projects. The experimental results show that our MD-CNN outperforms the existing representative bug localization techniques in terms of the Mean Average Precision (MAP) and the number of bugs successfully localized in the top 1, 5, and 10 matched source code files.

Software bugs are a noteworthy concern for developers and maintainers. When a failure is detected late, it costs more to be fixed. To repair the bug that caused the software failure, the location of the bug must first be known. The process of finding the defective source code elements that led to the failure of the software is called bug localization. Effective approaches for automatically locating bugs using bug reports are highly desirable, as they would reduce bug-fixing time, consequently lowering software maintenance costs. With the increasing size and complexity of software projects, manual bug localization methods have become complex, challenging, and time-consuming tasks, which motivates research on automated bug localization techniques. This paper introduces a novel bug localization model, which works on two levels. The first level localizes the buggy classes using an information retrieval approach and it has two additional sub-phases, namely the class-level feature scoring phase and the class-level final score and ranking phase, which ranks the top buggy classes. The second level localizes the buggy methods inside these classes using an information retrieval approach and it has two sub-phases, which are the method-level feature scoring phase and the method-level final score and ranking phase, which ranks the top buggy methods inside the localized classes. A model is evaluated using an AspectJ dataset, and it can correctly localize and rank more than 350 classes and more than 136 methods. The evaluation results show that the proposed model outperforms several state-of-the-art approaches in terms of the mean reciprocal rank (MRR) metrics and the mean average precision (MAP) in class-level bug localization.

Code search is an essential task in software development. Developers often search the internet and other code databases for necessary source code snippets to ease the development efforts. Code search techniques also help learn programming as novice programmers or students can quickly retrieve (hopefully good) examples already used in actual software projects. Given the recurrence of the code search activity in software development, there is an increasing interest in the research community. To improve the code search experience, the research community suggests many code search tools and techniques. These tools and techniques leverage several different ideas and claim a better code search performance. However, it is still challenging to illustrate a comprehensive view of the field considering that existing studies generally explore narrow and limited subsets of used components. This study aims to devise a grounded approach to understanding the procedure for code search and build an operational taxonomy capturing the critical facets of code search techniques. Additionally, we investigate evaluation methods, benchmarks, and datasets used in the field of code search.

The automated task of locating the potential buggy files in a software project given a bug report is called bug localization. Bug localization helps developers focus on crucial files. However, the existing automated bug localization approaches face a key challenge, called lexical mismatch. Specifically, the terms used in bug reports to describe a bug are different from the terms and code tokens used in source files. To address that, we present a novel approach that uses deep neural network (DNN) in combination with rVSM, an information retrieval (IR) technique. rVSM collects the feature on the textual similarity between bug reports and source files. DNN is used to learn to relate the terms in bug reports to potentially different code tokens and terms in source files. Our empirical evaluation on real-world bug reports in the open-source projects shows that DNN and IR complement well to each other to achieve higher bug localization accuracy than individual models. Importantly, our new model, DNNLOC, with a combination of the features built from DNN, rVSM, and project's bug-fixing history, achieves higher accuracy than the state-of-the-art IR and machine learning techniques. In half of the cases, it iscorrect with just a single suggested file. In 66% of the time, acorrect buggy file is in the list of three suggested files. With 5 suggested files, it is correct in almost 70% of the cases.

Software developers all over the world use Stack Overflow (SO) to interact and exchange code snippets. Research also uses SO to harvest code snippets for use with recommendation systems. However, previous work has shown that code on SO may have quality issues, such as security or license problems. We analyse Python code on SO to determine its coding style compliance. From 1,962,535 code snippets tagged with 'python', we extracted 407,097 snippets of at least 6 statements of Python code. Surprisingly, 93.87% of the extracted snippets contain style violations, with an average of 0.7 violations per statement and a huge number of snippets with a considerably higher ratio. Researchers and developers should, therefore, be aware that code snippets on SO may not representative of good coding style. Furthermore, while user reputation seems to be unrelated to coding style compliance, for posts with vote scores in the range between -10 and 20, we found a strong correlation (r = -0.87, p <; 10^-7) between the vote score a post received and the average number of violations per statement for snippets in such posts.

Bug localization, which aims to locate buggy files in the software project by leveraging bug reports, plays an important role in software quality control. Recently, many automatic bug localization methods based on historical bug-fix data (i.e., bug reports labeled with corresponding buggy code files) have been proposed. However, the lack of bug-fix data for software projects in the early stages of development limits the performance of most existing supervised learning methods. To address this issue, we propose a deep transfer bug localization model called TroBo, which can transfer shared knowledge from label-rich source project to the target project. Specifically, we accomplish the knowledge transfer on both the bug report and code file. For processing bug reports, which belong to informal text data, we design a soft attention-based module to alleviate the noise problem. For processing code files, we apply an adversarial strategy to learn the project-shared features, and additionally extract project-exclusive features for each project. Furthermore, a project-aware classifier is introduced in TroBo to avoid redundancy between shared and exclusive features. Extensive experiments on four large-scale real-world projects demonstrate that our model significantly outperforms the state-of-the-art techniques.

Reading and understanding source code is a major task in software development. Code comprehension depends on the quality of code, which is impacted by code structure and identifier naming. In this paper we empirically investigated whether longer but more descriptive identifier names improve code comprehension compared to short names, as they represent useful information in more detail. In a web-based study 88 Java developers were asked to locate a semantic defect in source code snippets. With descriptive identifier names, developers spent more time in the lines of code before the actual defect occurred and changed their reading direction less often, finding the semantic defect about 14% faster than with shorter but less descriptive identifier names. These effects disappeared when developers searched for a syntax error, i.e., when no in-depth understanding of the code was required. Interestingly, the style of identifier names had a clear impact on program comprehension for more experienced developers but not for less experienced developers.

Despite the extensive adoption of crowdsourcing for the timely, cost-effective, and high-quality completion of software development tasks, a large number of crowdsourced challenges are not able to acquire a winning solution, on time, and within the desired cost and quality thresholds. A possible reason for this is that we currently lack a systematic approach that would aid software managers during the process of designing software development tasks that will be crowdsourced. This paper attempts to extend the current knowledge on designing crowdsourced software development tasks, by empirically answering the following management questions: (a) what type of projects should be crowdsourced; (b) why should one crowdsource-in terms of acquired benefits; (c) where should one crowdsource-in terms of application domain; (d) when to crowdsource-referring to the time period of the year; (e) who will win or participate in the contest; and (f) how to crowdsource (define contest duration, prize, type of contest etc.) to acquire the maximum benefits-depending on the goal of crowdsourcing. To answer the aforementioned questions, we have performed a case study on 2,209 software development tasks crowdsourced through TopCoder platform. The results suggest that there are significant differences in the level to which crowdsourcing goals are reached, across different software development activities. Based on this observation we suggest that software managers should prioritize the goals of crowdsourcing, decide carefully upon the activity to be crowdsourced and then define the settings of the task.

In software testing and maintenance activities, the observed faults and bugs are reported in bug report managing systems (BRMS) for further analysis and repair. According to the information provided by bug reports, developers need to find out the location of these faults and fix them. However, bug locating usually involves intensively browsing back and forth through bug reports and software code and thus incurs unpredictable cost of labor and time. Hence, establishing a robust model to efficiently and effectively locate and track faults is crucial to facilitate software testing and maintenance. In our observation, some related bug locations are tightly associated with the implicit links among source files. In this paper, we present an implicit social network model using PageRank to establish a social network graph with the extracted links. When a new bug report arrives, the prediction model provides users with likely bug locations according to the implicit social network graph constructed from the co-cited source files. The proposed approach has been implemented in real-world software archives and can effectively predict correct bug locations.

Software development is a collaborative process in which programmers build software by integrating all the stages of the software development life cycle (SDLC). A software repository is a central file storage location where various software packages are stored, and these packages are retrieved and shared between all the software development team members at various locations. The software repositories are divided into various categories based on cooperation, coordination, and communication among the stakeholders as well as evolutionary changes to various software arti-facts such as source code repositories, software bug repositories, historical repositories, run-time repositories and requirement documents, and other documentation. The software bug repository is an essential repository among the entire repositories since the completion of the software is entirely dependent on the bug fixing mechanism associated with this repository in software development. Today's software systems are larger and more complex as they go through various stages from the requirement 98analysis phase to the maintenance phase. A variety of tasks and activities are carried out in each stage of software development, and these are expensive and vulnerable to errors. During software development, a large number of software bugs are continuously generated, and that has become the main reason for the delay in software completion. Hence, there is a vast demand for computational intelligent techniques to accomplish various tasks of software development. In recent years, fuzzy logic techniques emerged and played an important role in various fields of data mining and text mining. Since most of the content related to software bug repositories is text in nature, it is possible to effectively use fuzzy logic techniques to analyze these software bugs.

Software bug localization aiming to determine the locations needed to be fixed for a bug report is one of the most tedious and effort consuming activities in software debugging. Learning-to-rank (LR) is the state-of-the-art approach proposed by Ye et al. to recommending relevant files for bug localization. Ye et al.'s experimental results show that the LR approach significantly outperforms previous bug localization approaches in terms of precision and accuracy. However, this evaluation does not take into account the influence of the size of the recommended files on the efficiency in detecting bugs. In practice, developers will generally spend more code inspection effort to detect bugs if larger files are recommended. In this paper, we use six large-scale open-source Java projects to evaluate the LR approach in the context of effort-aware bug localization. Our results, surprisingly, show that, when taking into account the code inspection effort to detect bugs, the LR approach is similar to or even worse than the standard VSM (Vector Space Model), a naive IR-based bug localization approach.

Searching and reusing online code is a common activity in software development. Meanwhile, like many general-purposed searches, code search also faces the session search problem: in a code search session, the user needs to iteratively search for code snippets, exploring new code snippets that meet his/her needs and/or making some results highly ranked. This paper presents Cosoch, a reinforcement learning approach to session search of code documents (code snippets with textual explanations). Cosoch is aimed at generating a session that reveals user intentions, and correspondingly searching and reranking the resulting documents. More specifically, Cosoch casts a code search session into a Markov decision process, in which rewards measuring the relevances between the queries and the resulting code documents guide the whole session search. We have built a dataset, say CosoBe, from StackOverflow, containing 103 code search sessions with 378 pieces of user feedback. We have also evaluated Cosoch on CosoBe. The evaluation results show that Cosoch achieves an average NDCG@3 score of 0.7379, outperforming StackOverflow by 21.3%.

Software quality assurance is one of the crucial factors for the success of software projects. Bug fixing has an essential role in software quality assurance, and bug localization (BL) is the first step of this process. BL is difficult and time-consuming since the developers should understand the flow, coding structure, and the logic of the program. Information retrieval-based bug localization (IRBL) uses the information of bug reports and source code to locate the section of code in which the bug occurs. It is difficult to apply other tools because of the diversity of software development languages, design patterns, and development standards. The aim of this study is to build an adaptive IRBL tool and make it usable by more companies. BugSTAiR solves the aforementioned problem by means of the adaptive attribute weighting (AAW) algorithm and is evaluated on four open-source projects which are well-known benchmark datasets on BL. One of them is BLIA which is the state of the art in bug localization area and another is BLUIR which is a well-known BL tool. According to the promising results of experiments, Top1 rank of BugSTAiR is 2% and MAP is 10% better than BLIA's results on AspectJ and it has localized 4.6% of all bugs in Top1 and its precision is 6.1% better than BLIA on SWT, respectively. On the other side, it is 20% better in the Top1 metric and 30% in precision than BLUIR.