Lori Pollock

Matthew Frazier, Kostadin Damevski, Lori Pollock

Secondary school students enrolled in the AP Computer Science Principles (CSP) course commonly utilize web resources (e.g., tutorials, Q\&A sites) to better understand key concepts in the curriculum. The primary obstacle to using these resources is finding information appropriate for the learning task and student's background. In addition to web search, conversational agents are increasingly a viable alternative for CSP students. In this paper, we study the potential of conversational agents to aid secondary school students as they acquire knowledge on CSP concepts. We explore general purpose, generative conversational agents (e.g., ChatGPT) and custom, fixed-response conversational agents built specifically to aid CSP students. We present results from classroom use by 45 high school students in grades 9-11 (ages 14-17) across six CSP sections. Our main contributions are in better understanding how conversational agents can help CSP students and an evaluation of the effectiveness and engagement of different approaches for CSP exploratory search.

Shimul Debnath, William Hart, Lori Pollock et al.

Cloud performance fluctuates due to factors such as resource contention and workload changes. These factors can be short-term, seasonal, or long-term. Their effects are often intertwined in performance traces, making performance management difficult. Prior work on cloud performance engineering used time-series decomposition to separate these factors. However, existing approaches rely on basic decomposition methods that may miss key variation patterns and fail on traces with complex or intermittent patterns, limiting their usefulness across diverse cloud deployments. To address this limitation, we propose two time-series decomposition techniques for cloud performance engineering: a hybrid/manual method and a fully automatic method. Through a case study of 11 serverless functions, we show that both approaches can successfully and consistently reveal trends and seasonal cycles, such as weekly and quarterly patterns, which are otherwise obscured. As an evaluation and application of the decomposition, we used the decomposed components to predict future performance, yielding mean absolute percentage error (MAPE) values of only 1.8\% (hybrid) and 2.1\% (automatic), significantly outperforming basic time-series methods and deep learning. We further show that decomposition insights can guide practical resource allocation. Using decomposition-informed scaling on AWS, we reduced latency variability by over 60\% and maximum latency by 10\%. Similar experiments on benchmarks on AWS confirmed that seasonal patterns and performance gains generalize beyond our case study. Notably, our findings demonstrate that even a single performance trace contains rich actionable information for guiding cloud management decisions.

Kostadin Damevski, David Shepherd, Nicholas Kraft et al.

This is position paper accepted to the Computational Science & Engineering Software Sustainability and Productivity Challenges (CSESSP Challenges) Workshop, sponsored by the Networking and Information Technology Research and Development (NITRD) Software Design and Productivity (SDP) Coordinating Group, held October 15th-16th 2015 in Washington DC, USA. It discusses the role recommendation systems, based on textual and structural information in source code, and further enhanced by mining related applications, can have in improving the portability of scientific and engineering software.