VLDB 2026 Research / reviewers in the wild / expert
Piotr Przymus
dblp:31/10203
· DBLP profile ↗
19ranked-venue papers
12as first author
12since 2021 · last 2026
0000-0001-9548-2388ORCID · verified
Domains — the database's venue-derived domains; a paper can count in several
Databases, data management, data science and information retrieval · 14 · 9 first-author · 10 since 2021Software engineering, systems software and programming languages · 11 · 8 first-author · 11 since 2021Artificial intelligence and machine learning · 2 · 1 first-author · 2 since 2021Systems, architecture and hardware · 2 · 1 first-authorTheory of computation · 2 · 1 first-author · 1 since 2021Applied, interdisciplinary, general and emerging computing · 1 · 1 first-author · 1 since 2021
| Year | Publication | Venue | Position |
|---|---|---|---|
| 2026 | Underutilization in Research GPU Clusters: SE ChallengesabstractGPU clusters underpin modern deep learning, yet studies across industry and academia consistently report widespread GPU underutilization. Prior work and our own analysis indicate that inefficiency often stems from recurring patterns in code, job scripts, and runtime behaviour that users rarely detect. We argue that addressing this issue is a MSR challenge: it requires mining inefficiency patterns, combining static and dynamic signals for actionable feedback, validating job-submission artefacts, and developing privacy-aware datasets linking code, configuration, and runtime metrics. Krzysztof Kaczmarski, Jakub Narebski, Piotr Przymus |
MSR | 3 |
| 2026 | Can Data Mining Help to Survive the Annual Compiler Upgrade?abstractModern compilers provide improved diagnostics, performance, and security. The industry lacks the data and tools to estimate the cost to upgrade a compiler toolchain for complex projects. A knowledge base mined from defect databases, mailing lists, experience reports, commits, and grey literature will improve the planning process. Gunnar Kudrjavets, Piotr Przymus |
MSR | 3 |
| 2026 | Adversarial Bug Reports as a Security Risk in Language Model-Based Automated Program RepairabstractLarge Language Model (LLM) - based Automated Program Repair (APR) systems are increasingly integrated into modern software development workflows, offering automated patches in response to natural language bug reports. However, this reliance on untrusted user input introduces a novel and underexplored attack surface. In this paper, we investigate the security risks posed by adversarial bug reports—realistic-looking issue submissions crafted to mislead APR systems into producing insecure or harmful code changes. We develop a comprehensive threat model and conduct an empirical study to evaluate the vulnerability of APR systems to such attacks. Our demonstration comprises 51 adversarial bug reports generated across a spectrum of strategies, ranging from manual curation to fully automated pipelines. We test these against a leading LLM-based APR system and assess both pre-repair defenses (e.g., LlamaGuard variants, PromptGuard variants, Granite-Guardian, and custom LLM filters) and post-repair detectors (GitHub Copilot, CodeQL). Our findings show that current defenses are insufficient: 90% of crafted bug reports triggered attacker-aligned patches. The best pre-repair filter blocked only 47%, while post-repair analysis—often requiring human oversight—was effective in just 58% of cases. To support scalable security testing, we introduce a prototype framework for automating the generation of adversarial bug reports. Our analysis exposes a structural asymmetry: generating adversarial inputs is inexpensive, while detecting or mitigating them remains costly and error-prone. We conclude with recommendations for improving the robustness of APR systems against adversarial misuse and highlight directions for future work on secure APR. Piotr Przymus, Andreas Happe, Jürgen Cito |
MSR | 1 |
| 2026 | Linux Kernel Recency Matters, CVE Severity Doesn't, and History FadesabstractIn 2024, the Linux kernel became its own Common Vulnerabilities and Exposures (CVE) Numbering Authority (CNA), formalizing how kernel vulnerabilities are identified and tracked. We analyze the anatomy and dynamics of kernel CVEs using metadata, associated commits, and patch latency to understand what drives patching. Results show that severity and Common Vulnerability Scoring System (CVSS) metrics have a negligible association with patch latency, whereas kernel recency is a reasonable predictor in survival models. Kernel developers fix newer kernels sooner, while older ones retain unresolved CVEs. Commits introducing vulnerabilities are typically broader and more complex than their fixes, though often only approximate reconstructions of development history. The Linux kernel remains a unique open-source project—its CVE process is no exception. Piotr Przymus, Witold Weiner, Krzysztof Rykaczewski, Gunnar Kudrjavets |
MSR | 1 |
| 2025 | Segmentation and Process Assignment of Semi-Structured Event LogsabstractProcess mining provides valuable insights by discovering process models from execution logs.However, its effectiveness depends heavily on high-quality, well-structured logs.Many real-world systems produce low-level, semi-structured logs lacking clear process identifiers, causing misalignment with their intended process models.This paper introduces a method for structuring raw event logs by segmenting event streams and mapping them to known processes.Using process traces from experienced users, we develop a model that infers process assignments in unstructured logs.Our approach is motivated by a modular enterprise system without predefined workflows, where dynamic processes generate low-level logs requiring interpretation.We validate our method on a semi-synthetic business dataset and a fully synthetic dataset from PLG2.Our results demonstrate that trace segmentation improves process discovery, aligns logs with meaningful structures, and significantly enhances process mining in unstructured environments.This work was supported by the Regional Operational Programme of the Kuyavian-Pomeranian Voivodeship for 2014-2020 under the grant titled "Budowa zaplecza badawczo-rozwojowego w MGA Sp. z o.o." variability of clients, the heterogeneity of business processes, and the system's flexibility, incorporating process identifiers into the logs is not feasible from a business perspective.Therefore, our methodology relies exclusively on semi-structured data.By implementing this approach, we provide a solution that enhances process mining capabilities in environments where structured event logs are unavailable.This research contributes to process mining by introducing a method for structuring semi-structured event logs, enabling more effective business process analysis, anomaly detection, and performance monitoring.a) Replication Package: To facilitate reproducibility and further research, we provide a complete replication package containing code, data, and experimental scripts.It is publicly available at:The remainder of this paper is organized as follows.Section II discusses related work.Sections III and IV reviews necessary preliminaries on event logs, process mining, and similarity measures.Section V states the problem, and Section VI describes our methodology for structuring semi-structured event logs.In Section VII, we discuss our experimental design, and Section VIII presents the results.In Section IX, we assess threats to validity.Finally, we conclude and propose future directions in Section X. A. Running Example (Motivation)Consider a customer-support system where each event is logged as [time, user, activity, . ..].A typical log snippet might look like: Piotr Przymus, Krzysztof Rykaczewski, Janusz Zielinski, Lukasz Mikulski |
FedCSIS | 1 |
| 2025 | Wolves in the Repository: A Software Engineering Analysis of the XZ Utils Supply Chain AttackabstractThe digital economy runs on Open Source Software (OSS), with an estimated 90% of modern applications containing open-source components. While this widespread adoption has revolutionized software development, it has also created critical security vulnerabilities, particularly in essential but underresourced projects. This paper examines a sophisticated attack on the XZ Utils project (CVE-2024-3094), where attackers exploited not just code, but the entire open-source development process to inject a backdoor into a fundamental Linux compression library. Our analysis reveals a new breed of supply chain attack that manipulates software engineering practices themselves - from community management to CI/CD configurations - to establish legitimacy and maintain long-term control. Through a comprehensive examination of GitHub events and development artifacts, we reconstruct the attack timeline, analyze the evolution of attacker tactics. Our findings demonstrate how attackers leveraged seemingly beneficial contributions to project infrastructure and maintenance to bypass traditional security measures. This work extends beyond traditional security analysis by examining how software engineering practices themselves can be weaponized, offering insights for protecting the open-source ecosystem. Piotr Przymus, Thomas Durieux |
MSR | 1 |
| 2025 | Out of Sight, Still at Risk: The Lifecycle of Transitive Vulnerabilities in MavenabstractThe modern software development landscape heavily relies on transitive dependencies. They enable seamless integration of third-party libraries. However, they also introduce security challenges. Transitive vulnerabilities that arise from indirect dependencies expose projects to risks associated with Common Vulnerabilities and Exposures (CVEs). It happens even when direct dependencies remain secure. This paper examines the lifecycle of transitive vulnerabilities in the Maven ecosystem. We employ survival analysis to measure the time projects remain exposed after a CVE is introduced. Using a large dataset of Maven projects, we identify factors that influence the resolution of these vulnerabilities. Our findings offer practical advice on improving dependency management. Piotr Przymus, Mikolaj Fejzer, Jakub Narebski, Krzysztof Rykaczewski, Krzysztof Stencel |
MSR | 1 |
| 2025 | HaPy-Bug - Human Annotated Python Bug Resolution DatasetabstractWe present HaPy-Bug, a curated dataset of 793 Python source code commits associated with bug fixes, with each line of code annotated by three domain experts. The annotations offer insights into the purpose of modified files, changes at the line level, and reviewers’ confidence levels. We analyze HaPy-Bug to examine the distribution of file purposes, types of modifications, and tangled changes. Additionally, we explore its potential applications in bug tracking, the analysis of bug-fixing practices, and the development of repository analysis tools. HaPy-Bug serves as a valuable resource for advancing research in software maintenance and security. Piotr Przymus, Mikolaj Fejzer, Jakub Narebski, Radoslaw Wozniak, Lukasz Halada, Aleksander Kazecki, Mykhailo Molchanov, Krzysztof Stencel |
MSR | 1 |
| 2024 | How I Learned to Stop Worrying and Love ChatGPTabstractIn the dynamic landscape of software engineering, the emergence of ChatGPT-generated code signifies a distinctive and evolving paradigm in development practices. We delve into the impact of interactions with ChatGPT on the software development process, specifically analysing its influence on source code changes. Our emphasis lies in aligning code with ChatGPT conversations, separately analysing the user-provided context of the code and the extent to which the resulting code has been influenced by ChatGPT. Additionally, employing survival analysis techniques, we examine the longevity of ChatGPT-generated code segments in comparison to lines written traditionally. The goal is to provide valuable insights into the transformative role of ChatGPT in software development, illuminating its implications for code evolution and sustainability within the ecosystem. Piotr Przymus, Mikolaj Fejzer, Jakub Narebski, Krzysztof Stencel |
MSR | 1 |
| 2023 | The Secret Life of CVEsabstractThe Common Vulnerabilities and Exposures (CVEs) system is a reference method for documenting publicly known information security weaknesses and exposures. This paper presents a study of the lifetime of CVEs in software projects and the risk factors affecting their existence. The study uses survival analysis to examine how features of programming languages, projects, and CVEs themselves impact the lifetime of CVEs. We suggest avenues for future research to investigate the effect of various factors on the resolution of vulnerabilities. Piotr Przymus, Mikolaj Fejzer, Jakub Narebski, Krzysztof Stencel |
MSR | 1 |
| 2022 | Fast JSON parser using metaprogramming on GPUabstractWe demonstrate a new idea of a parallel GPU JSON parser, which is able to optimize the parsing and initial transformation process through metaprogramming. It outperforms other well-known solutions like simdjson, Pandas, as well as cuDF– which also works on GPU. The resulting data is ready to be further processed in common data frame formats and may be incorporated by RAPIDS, Apache Arrow or Pandas. Our parser can therefore be a part of an industrial Extract-Transform-Load workflow. Krzysztof Kaczmarski, Jakub Narebski, Stanislaw Piotrowski, Piotr Przymus |
DSAA | 4 |
| 2022 | Tracking Buggy Files: New Efficient Adaptive Bug Localization AlgorithmabstractUpon receiving a new bug report, developers need to find its cause in the source code. Bug localization can be helped by a tool that ranks all source files according to how likely they include the bug. This problem was thoroughly examined by numerous scientists. We introduce a novel adaptive bug localization algorithm. The concept behind it is based on new feature weighting approaches and an adaptive selection algorithm utilizing pointwise learn–to–rank method. The algorithm is evaluated on publicly available datasets, and is competitive in terms of accuracy and required computational resources compared to state–of–the–art. Additionally, to improve reproducibility we provide extended datasets that include computed features and partial steps, and we also provide the source code. Mikolaj Fejzer, Jakub Narebski, Piotr Przymus, Krzysztof Stencel |
IEEE Trans. Software Eng. | 3 |
| 2018 | Profile based recommendation of code reviewersabstractCode reviews consist in proof-reading proposed code changes in order to find their shortcomings such as bugs, insufficient test coverage or misused design patterns. Code reviews are conducted before merging submitted changes into the main development branch. The selection of suitable reviewers is crucial to obtain the high quality of reviews. In this article we present a new method of recommending reviewers for code changes. This method is based on profiles of individual programmers. For each developer we maintain his/her profile. It is the multiset of all file path segments from commits reviewed by him/her. It will get updated when he/she presents a new review. We employ a similarity function between such profiles and change proposals to be reviewed. The programmer whose profile matches the change most is recommended to become the reviewer. We performed an experimental comparison of our method against state-of-the-art techniques using four large open-source projects. We obtained improved results in terms of classification metrics (precision, recall and F-measure) and performance (we have lower time and space complexity). Mikolaj Fejzer, Piotr Przymus, Krzysztof Stencel |
J. Intell. Inf. Syst. | 2 |
| 2017 | Fixed length lightweight compression for GPU revised
Krzysztof Kaczmarski, Piotr Przymus |
J. Parallel Distributed Comput. | 2 |
| 2014 | Improving High-Performance GPU Graph Traversal with Compression
Krzysztof Kaczmarski, Piotr Przymus, Pawel Rzazewski |
ADBIS (2) | 2 |
| 2014 | Zebra mussels' behaviour detection, extraction and classification using wavelets and kernel methods
Piotr Przymus, Krzysztof Rykaczewski, Ryszard Wisniewski |
Future Gener. Comput. Syst. | 1 |
| 2014 | A Bi-objective Optimization Framework for Heterogeneous CPU/GPU Query PlansabstractGraphics Processing Units (GPU) have significantly more applications than just rendering images. They are also used in general-purpose computing to solve problems that can benefit from massive parallel processing. However, there are tasks that either hardly suit GPU or fit GPU only partially. The latter class is the focus of this paper. We elaborate on hybrid CPU/GPU computation and build optimization methods that seek the equilibrium between these two computation platforms. The method is based on heuristic search for bi-objective Pareto optimal execution plans in presence of multiple concurrent queries. The underlying model mimics the commodity market where devices are producers and queries are consumers. The value of resources of computing devices is controlled by supply-and-demand laws. Our model of the optimization criteria allows finding solutions of problems not yet addressed in heterogeneous query processing. Furthermore, it also offers lower time complexity and higher accuracy than other methods. Piotr Przymus, Krzysztof Kaczmarski, Krzysztof Stencel |
Fundam. Informaticae | 1 |
| 2013 | Time Series Queries Processing with GPU Support
Piotr Przymus, Krzysztof Kaczmarski |
ADBIS (2) | 1 |
| 2013 | Dynamic Compression Strategy for Time Series Database Using GPU
Piotr Przymus, Krzysztof Kaczmarski |
ADBIS (2) | 1 |