基于源代码扩展信息的细粒度缺陷定位方法

基于信息检索的缺陷定位技术,利用跨语言的语义相似性构造检索模型,通过缺陷报告定位源代码错误,具有方法直观、通用性强的特点.但是由于传统基于信息检索的缺陷定位方法将代码作为纯文本进行处理,只利用了源代码的词汇语义信息,导致在细粒度缺陷定位中面临候选代码语义匮乏产生的准确性低的问题,其结果有用性还有待改进.通过分析程序演化场景下代码改动与缺陷产生间的关系,提出一种基于源代码扩展信息的细粒度缺陷定位方法,以代码词汇语义显性信息及代码执行隐性信息共同丰富源代码语义实现细粒度缺陷定位.利用定位候选点的语义相关上下文丰富代码量,以代码执行中间形式的结构语义实现细粒度代码的可区分,同时以自然语言语义指导基于注意力机制的代码语言表征生成,实现细粒度代码与自然语言间的语义映射,从而实现细粒度缺陷定位方法FlowLocator.实验分析结果表明：与经典的IR缺陷定位方法相比,该方法定位准确性在Top-N排名、平均准确率及平均倒数排名上都有显著提高.     

基于缺陷修复历史的两阶段缺陷定位方法

缺陷定位是软件缺陷修复的关键步骤。随着计算机软件的日趋复杂和网络的迅速发展,如何快速高效的定位缺陷相关代码成为了一个急待解决的问题。在研究现有基于信息检索技术的缺陷定位方法的基础上,综合考虑缺陷修复历史信息,提出了基于缺陷修复历史的两阶段缺陷定位方法。该方法不再单一依赖文本相似度,从缺陷修复的局部性现象入手,更多的考虑了缺陷修复的历史记录、变更信息及代码特征等因素,结合信息检索和缺陷预测方法来提高缺陷定位的精度。最后本文以两个开源项目为例,验证了方法的可行性和有效性。     

基于信息检索的软件缺陷定位技术研究进展

缺陷定位是软件工程研究最活跃的领域之一.大部分软件缺陷都会被提交到类似于Bugzilla和Jira的缺陷追踪系统中.由于提交的缺陷报告数量过多,开发人员不能及时地处理,因而迫切需要一个自动化工具来帮助开发人员识别缺陷相关源代码文件.研究人员已经提出了大量的缺陷定位技术.基于信息检索的软件缺陷定位技术（Information Retrieval-based Bug Localization,简称IRBL）利用了缺陷报告的文本特性,并且由于计算成本低、对不同的程序语言更具有普适性,成为缺陷定位领域的研究热点,取得了一系列研究成果.然而,IRBL技术也在数据预处理、相似度计算和工程应用等方面存在诸多挑战.鉴于此,本文对现有的IRBL技术进行梳理总结.主要内容包括：（1）梳理了IRBL中数据预处理的过程和信息检索通用方法;（2）对IRBL技术中利用的数据特征进行了详细的分类和总结;（3）总结了技术评估中使用的性能评估指标;（4）归纳出了IRBL技术的关键问题;（5）最后展望了IRBL技术的未来发展.     

基于代价敏感间隔分布优化的软件缺陷定位

在大型软件项目的开发与维护中,从大量的代码文件中定位软件缺陷费时、费力,有效地进行软件缺陷自动定位,将能极大地降低开发成本.软件缺陷报告通常包含了大量未发觉的软件缺陷的信息,精确地寻找与缺陷报告相关联的代码文件,对于降低维护成本具有重要意义.目前,已有一些基于深度神经网络的缺陷定位技术相对于传统方法,其效果有所提升,但相关工作大多关注网络结构的设计,缺乏对训练过程中损失函数的研究,而损失函数对于预测任务的性能会有极大的影响.在此背景下,提出了代价敏感的间隔分布优化（cost-sensitive margin distribution optimization,简称CSMDO）损失函数,并将代价敏感的间隔分布优化层应用到深度卷积神经网络中,能够良好地处理软件缺陷数据的不平衡性,进一步提高缺陷定位的准确度.     

Firefox缺陷跟踪系统中的用户反馈

缺陷追踪是软件项目管理的一个重要环节，是保证现代大规模开源软件开发顺利进行并持续提高软件质量的必要手段.目前，大部分开源软件都使用开放的缺陷跟踪系统进行软件缺陷的管理.它允许用户向开发者提交系统故障（即defect类型缺陷）以及系统改进建议（即enhancement类型缺陷），但是这些用户的反馈所起的作用尚未得到充分研究.针对这一问题，对Firefox的缺陷跟踪系统进行实证研究，收集了2018年和2019年提交的19 474份Firefox Desktop以及3 057份Firefox for Android缺陷报告.在此基础上，对比分析了普通用户和核心开发者提交的缺陷在数量、严重性、组件分布、修复率、修复速度以及修复者上的差别，并调查了缺陷报告的撰写质量与缺陷处理结果和修复时间的关系.主要发现包括：（1）当前缺陷追踪系统中普通用户人数众多，但参与程度较浅，86%的用户只提交过一个缺陷，其中，高严重等级的缺陷不超过3%；（2）普通用户提交的缺陷主要分布在和用户交互相关的UI组件上（例如地址栏、音频/视频等），然而还有43%的缺陷由于缺乏充分描述信息而难以准确地定位到具体的关联组件；（3）在缺陷处理结果上，由于查重系统以及缺陷填报系统在设计上过于简单，致使普通用户提交的大量缺陷被处理为“无用”缺陷，缺陷修复率低于10%；（4）在缺陷修复流程上，由于普通用户难以准确、充分地描述缺陷，导致系统对其重视程度不足，普通用户提交缺陷的处理流程也比核心开发者提交的复杂，平均需要多花至少8天的时间进行修复.上述研究结果揭示了当前缺陷追踪系统在用户参与激励机制、缺陷自动查重以及缺陷报告填写智能辅助等方面的不足，能够为缺陷跟踪系统开发者和管理者改进系统、提高普通用户对开源软件的贡献提供参考.     

基于高斯过程的缺陷定位方法

在软件系统中,缺陷定位是缺陷修复的一个关键环节,如果能将缺陷自动定位到很小的范围,将会极大地降低缺陷修复的难度.基于高斯过程提出了一种缺陷定位方法（GPBL）,即针对每个缺陷,向开发人员推荐这个缺陷可能存在于哪些源文件中,从而帮助开发人员快速修复缺陷.为了验证方法的有效性,采集了开源软件Eclipse 和Argouml 中的数据,实验结果表明,高斯过程缺陷定位的查全率和查准率平均分别为87.16%和78.90%.与基于LDA的缺陷定位方法进行比较,表明高斯过程更能准确定位缺陷的位置.     

Eye movements in software traceability link recovery

Information Retrieval (IR) approaches, such as Latent Semantic Indexing (LSI) and Vector Space Model (VSM), are commonly applied to recover software traceability links. Recently, an approach based on developers’ eye gazes was proposed to retrieve traceability links. This paper presents a comparative study on IR and eye-gaze based approaches. In addition, it reports on the possibility of using eye gaze links as an alternative benchmark in comparison to commits. The study conducted asked developers to perform bug-localization tasks on the open source subject system JabRef. The iTrace environment, which is an eye tracking enabled Eclipse plugin, was used to collect eye gaze data. During the data collection phase, an eye tracker was used to gather the source code entities (SCE’s), developers looked at while solving these tasks. We present an algorithm that uses the collected gaze dataset to produce candidate traceability links related to the tasks. In the evaluation phase, we compared the results of our algorithm with the results of an IR technique, in two different contexts. In the first context, precision and recall metric values are reported for both IR and eye gaze approaches based on commits. In the second context, another set of developers were asked to rate the candidate links from each of the two techniques in terms of how useful they were in fixing the bugs. The eye gaze approach outperforms standard LSI and VSM approaches and reports a 55 % precision and 67 % recall on average for all tasks when compared to how the developers actually fixed the bug. In the second context, the usefulness results show that links generated by our algorithm were considered to be significantly more useful (to fix the bug) than those of the IR technique in a majority of tasks. We discuss the implications of this radically different method of deriving traceability links. Techniques for feature location/bug localization are commonly evaluated on benchmarks formed from commits as is done in the evaluation phase of this study. Although, commits are a reasonable source, they only capture entities that were eventually changed to fix a bug or resolve a feature. We investigate another type of benchmark based on eye tracking data, namely links generated from the bug-localization tasks given to the developers in the data collection phase. The source code entities relevant to subjected bugs recommended from IR methods are evaluated on both commits and links generated from eye gaze. The results of the benchmarking phase show that the use of eye tracking could form an effective (complementary) benchmark and add another interesting perspective in the evaluation of bug-localization techniques.     

基于信息检索的缺陷定位:问题、进展与挑战

缺陷的存在,会影响软件系统的正常使用甚至带来重大危害.为了帮助开发者尽快找到并修复这些缺陷,研究者提出了基于信息检索的缺陷定位方法.这类方法将缺陷定位视为一个检索任务,它为每个缺陷报告生成一份按照程序实体与缺陷相关度降序排序的列表.开发者可以根据列表顺序来审查代码,从而降低审查成本并加速缺陷定位的进程.近年来,该领域的研究工作十分活跃,在改良定位方法和完善评价体系方面取得了较大进展.与此同时,为了能够在实践中更好地应用这类方法,该领域的研究工作仍面临着一些亟待解决的挑战.对近年来国内外学者在该领域的研究成果进行系统性的总结：首先,描述了基于信息检索的缺陷定位方法的研究问题;然后,分别从模型改良和模型评估两方面陈述了相关的研究进展,并对具体的理论和技术途径进行梳理;接着,简要介绍了缺陷定位的其他相关技术;最后,总结了目前该领域研究过程中面临的挑战并给出建议的研究方向.     

Hybrid followee recommendation in microblogging systems

Bug reports are widely employed to facilitate software tasks in software maintenance. Since bug reports are contributed by people, the authorship characteristics of contributors may heavily impact the perfor-mance of resolving software tasks. Poorly written bug reports may delay developers when fixing bugs. However, no in-depth investigation has been conducted over the authorship characteristics. In this study, we first leverage byte-level N-grams to model the authorship characteristics and employ Normalized Simplified Profile Intersection (NSPI) to identify the similarity of the authorship characteristics. Then, we investigate a series of properties related to contributors’ authorship characteristics, including the evolvement over time and the variation among distinct products in open source projects. Moreover, we show how to leverage the authorship characteristics to facilitate a well-known task in software maintenance, namely Bug Report Summarization (BRS). Experiments on open source projects validate that incorporating the authorship characteristics can effectively improve a state-of-the-art method in BRS. Our findings suggest that contributors should retain stable authorship characteristics and the authorship characteristics can assist in resolving software tasks.

     

知识驱动的相似缺陷报告推荐方法

软件缺陷在软件开发过程中不可避免,提交的缺陷报告则是分析和修复缺陷的重要信息来源。开发人员常通过借鉴相似的历史缺陷报告和修复信息来辅助对当前新缺陷的分析和修复。文中提出了一种知识驱动的相似缺陷报告推荐方法。该方法首先利用信息检索和Word Embedding技术构建缺陷知识图谱;然后利用TF-IDF和Word Embedding技术计算缺陷报告之间的文本相似度,同时综合考虑缺陷的各项属性,从而得到缺陷报告之间的主次要属性相似度;最后将上述相似度融合成综合相似度,利用综合相似度推荐相似缺陷报告。实验结果表明,与基线方法相比,在Firefox数据集上所提方法的性能平均提高了12.7%。     

Understanding the triaging and fixing processes of long lived bugs

ContextBug fixing is an integral part of software development and maintenance. A large number of bugs often indicate poor software quality, since buggy behavior not only causes failures that may be costly but also has a detrimental effect on the user’s overall experience with the software product. The impact of long lived bugs can be even more critical since experiencing the same bug version after version can be particularly frustrating for user. While there are many studies that investigate factors affecting bug fixing time for entire bug repositories, to the best of our knowledge, none of these studies investigates the extent and reasons of long lived bugs.ObjectiveIn this paper, we investigate the triaging and fixing processes of long lived bugs so that we can identify the reasons for delay and improve the overall bug fixing process.MethodologyWe mine the bug repositories of popular open source projects, and analyze long lived bugs from five different perspectives: their proportion, severity, assignment, reasons, as well as the nature of fixes.ResultsOur study on seven open-source projects shows that there are a considerable number of long lived bugs in each system and over 90% of them adversely affect the user’s experience. The reasons for these long lived bugs are diverse including long assignment time, not understanding their importance in advance, etc. However, many bug-fixes were delayed without any specific reasons. Furthermore, 40% of long lived bugs need only small fixes.ConclusionOur overall results suggest that a significant number of long lived bugs may be minimized through careful triaging and prioritization if developers could predict their severity, change effort, and change impact in advance. We believe our results will help both developers and researchers better to understand factors behind delays, improve the overall bug fixing process, and investigate analytical approaches for prioritizing bugs based on bug severity as well as expected bug fixing effort.     

融合信息检索和深度模型特征的软件缺陷定位方法

构建自动化的缺陷定位方法能够加快程序员利用缺陷报告定位到复杂软件系统缺陷代码的过程.早期相关研究人员将缺陷定位视为检索任务,通过分析缺陷报告和相关代码构造缺陷特征,并结合信息检索的方法实现缺陷定位.随着深度学习的发展,利用深度模型特征的缺陷定位方法也取得了一定效果.然而,由于深度模型训练的时间成本和耗费资源相对较高,现有基于深度模型的缺陷定位研究方法存在实验搜索空间和真实情况不符的情况.这些研究方法在测试时并没有将项目下的所有代码作为搜索空间,而仅仅搜索了与已有缺陷相关的代码, 例如DNNLOC方法,DeepLocator方法,DreamLoc方法.这种做法和现实中程序员进行缺陷定位的搜索场景是不一致的.致力于模拟缺陷定位的真实场景,本文提出了一种融合信息检索和深度模型特征的TosLoc方法进行缺陷定位.TosLoc方法首先通过信息检索的方式检索真实项目的所有源代码,确保已有特征的充分利用;再利用深度模型挖掘源代码和缺陷报告的语义,获取最终定位结果.通过两阶段的检索,TosLoc方法能够对单个项目的所有代码实现快速缺陷定位.通过在4个常用的真实Java项目上进行实验,本文提出的TosLoc方法能在检索速度和准确性上超越已有基准方法.和最优基准方法DreamLoc相比,TosLoc方法在消耗DreamLoc方法35%的检索时间下,平均MRR值比DreamLoc方法提高了2.5%,平均MAP值提高了6.0%.     

基于代价极速学习机的软件缺陷报告分类方法

在所有的软件系统开发过程中,Bug的存在是不可避免的问题.对于软件系统的开发者来说,修复Bug最有利的工具就是Bug报告.但是人工识别Bug报告会给开发人员带来新的负担,因此,自动对Bug报告进行分类是一项很有必要的工作.基于此,提出用基于极速学习机的方法来对Bug报告进行分类.具体而言,主要解决Bug报告自动分类的3个问题：第1个是Bug报告数据集里不同类别的样本数量不平衡问题;第2个是Bug报告数据集里被标注的样本不充足问题;第3个是Bug报告数据集总体样本量不充足问题.为了解决这3个问题,分别引入了基于代价的有监督分类方法、基于模糊度的半监督学习方法以及样本迁移方法.通过在多个Bug报告数据集上进行实验,验证了这些方法的可行性和有效性.     

基于信息检索的软件缺陷定位方法综述

基于信息检索的软件缺陷定位方法是当前软件缺陷定位领域中的一个研究热点.该方法主要分析缺陷报告文本和程序模块代码,通过计算缺陷报告和程序模块间的相似度,选取与缺陷报告相似度最高的若干程序模块,将其推荐给开发人员.本文对近些年国内外研究人员在该综述主题上取得的成果进行了系统的梳理和总结.首先,给出研究框架并阐述影响方法性能的三个重要因素：数据源、检索模型和场景应用;其次,依次对这三个影响因素的已有研究成果进行总结;然后,总结基于信息检索的软件缺陷定位研究中常用的性能评测指标和评测数据集;最后总结全文并对未来值得关注的研究方向进行展望.     

面向软件缺陷报告的提取方法

软件工程中的软件缺陷报告数量在快速增长,开发者们越来越困惑于大量的缺陷报告。因此,为了达到缺陷修复和软件复用等目的,有必要研究软件缺陷报告的提取方法。提出一种提取方法,该方法首先合并缺陷报告中的同义词,然后建立空间向量模型,使用词频反文档频率以及信息增益等文本挖掘的方法来收集软件缺陷报告中单词的特征,同时设计算法来确定句子复杂度以选择长句,最后将贝叶斯分类器引入该领域。该方法可以提高缺陷报告提取的命中率,降低虚警率。实验证明,基于文本挖掘和贝叶斯分类器的软件缺陷报告提取方法在接受者工作特征曲线面积(0.71)、F-score(0.80)和Kappa值(0.75)方面有良好效果。     

Bug localization using latent Dirichlet allocation

ContextSome recent static techniques for automatic bug localization have been built around modern information retrieval (IR) models such as latent semantic indexing (LSI). Latent Dirichlet allocation (LDA) is a generative statistical model that has significant advantages, in modularity and extensibility, over both LSI and probabilistic LSI (pLSI). Moreover, LDA has been shown effective in topic model based information retrieval. In this paper, we present a static LDA-based technique for automatic bug localization and evaluate its effectiveness.ObjectiveWe evaluate the accuracy and scalability of the LDA-based technique and investigate whether it is suitable for use with open-source software systems of varying size, including those developed using agile methods.MethodWe present five case studies designed to determine the accuracy and scalability of the LDA-based technique, as well as its relationships to software system size and to source code stability. The studies examine over 300 bugs across more than 25 iterations of three software systems.ResultsThe results of the studies show that the LDA-based technique maintains sufficient accuracy across all bugs in a single iteration of a software system and is scalable to a large number of bugs across multiple revisions of two software systems. The results of the studies also indicate that the accuracy of the LDA-based technique is not affected by the size of the subject software system or by the stability of its source code base.ConclusionWe conclude that an effective static technique for automatic bug localization can be built around LDA. We also conclude that there is no significant relationship between the accuracy of the LDA-based technique and the size of the subject software system or the stability of its source code base. Thus, the LDA-based technique is widely applicable.     

Bug Triaging Based on Tossing Sequence Modeling

Bug triaging, which routes the bug reports to potential fixers, is an integral step in software development and maintenance. To make bug triaging more efficient, many researchers propose to adopt machine learning and information retrieval techniques to identify some suitable fixers for a given bug report. However, none of the existing proposals simultaneously take into account the following three aspects that matter for the efficiency of bug triaging:1) the textual content in the bug reports, 2) the metadata in the bug reports, and 3) the tossing sequence of the bug reports. To simultaneously make use of the above three aspects, we propose iTriage which first adopts a sequence-to-sequence model to jointly learn the features of textual content and tossing sequence, and then uses a classification model to integrate the features from textual content, metadata, and tossing sequence. Evaluation results on three different open-source projects show that the proposed approach has significantly improved the accuracy of bug triaging compared with the state-of-the-art approaches.     

Studying re-opened bugs in open source software

Bug fixing accounts for a large amount of the software maintenance resources. Generally, bugs are reported, fixed, verified and closed. However, in some cases bugs have to be re-opened. Re-opened bugs increase maintenance costs, degrade the overall user-perceived quality of the software and lead to unnecessary rework by busy practitioners. In this paper, we study and predict re-opened bugs through a case study on three large open source projects—namely Eclipse, Apache and OpenOffice. We structure our study along four dimensions: (1) the work habits dimension (e.g., the weekday on which the bug was initially closed), (2) the bug report dimension (e.g., the component in which the bug was found) (3) the bug fix dimension (e.g., the amount of time it took to perform the initial fix) and (4) the team dimension (e.g., the experience of the bug fixer). We build decision trees using the aforementioned factors that aim to predict re-opened bugs. We perform top node analysis to determine which factors are the most important indicators of whether or not a bug will be re-opened. Our study shows that the comment text and last status of the bug when it is initially closed are the most important factors related to whether or not a bug will be re-opened. Using a combination of these dimensions, we can build explainable prediction models that can achieve a precision between 52.1–78.6 % and a recall in the range of 70.5–94.1 % when predicting whether a bug will be re-opened. We find that the factors that best indicate which bugs might be re-opened vary based on the project. The comment text is the most important factor for the Eclipse and OpenOffice projects, while the last status is the most important one for Apache. These factors should be closely examined in order to reduce maintenance cost due to re-opened bugs.     

版本失配和数据泄露对基于缺陷报告的缺陷定位模型的影响

为了降低缺陷定位过程中的人力成本,研究者们在缺陷报告的基础上提出了许多基于信息检索的缺陷定位模型,包括使用传统特征和使用深度学习特征进行建模的定位模型.在评价不同缺陷定位模型时设计的实验中,现有研究大多忽视了缺陷报告所属的版本与目标源代码的版本之间存在的“版本失配”问题或/和在训练和测试模型时缺陷报告的时间顺序所引发的“数据泄露”问题.致力于报告现有模型在更加真实的应用场景下的性能表现,并分析版本失配和数据泄露问题对评估各模型真实性能产生的影响.选取6个使用传统特征的定位模型(BugLocator、BRTracer、BLUiR、AmaLgam、BLIA、Locus)和1个使用深度学习特征的定位模型(CodeBERT)作为研究对象.在5个不同实验设置下基于8个开源项目进行系统性的实证分析.首先, CodeBERT模型直接应用于缺陷定位效果并不理想,其定位的准确率依赖于目标项目的版本数目和源代码规模.其次,版本匹配设置下使用传统特征的定位模型在平均准确率均值(MAP)、平均序位倒数均值(MRR)两个指标上比版本失配实验设置下最高可以提高47.2%和46.0%, CodeBERT模型的效果也...