Event Details
Ensuring Ergodicity in Large-Scale Distributed Software Systems: Theory, Challenges, and Solutions
Presenter: Zahra Nikdel
Supervisor:
Date: Fri, August 9, 2024
Time: 13:00:00 - 00:00:00
Place: Zoom, link below.
ABSTRACT
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Meeting ID: 895 3534 3960
Password: 091121
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Meeting ID: 895 3534 3960
Password: 091121
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ABSTRACT
In this seminar, we explore the concept of ergodicity in software-centric systems, ranging from simple embedded systems to complex distributed ones in commercial clouds. Modern software technologies increasingly utilize control theory and machine learning to address challenges such as performance prediction and reliability analysis. These methodologies presuppose that the systems in question are both ergodic and stationary, enabling future behavior predictions based on historical data. We begin by modeling stochastic runtime performance measures as dynamical systems, focusing on macro-level observables like average response times. The seminar will cover formal definitions of statistical stationarity and ergodic theory, highlighting Birkhoff's Ergodic Theorem (BET) and Peter Walters' conditions for testing ergodicity. The discussion then shifts to the applicability of these theories to large-scale distributed systems (LDSS). We identify that while some conditions are easily applicable, others present significant challenges. Factors such as fair scheduling, server overloading, queue drops, and reliable protocols are analyzed for their impact on maintaining ergodicity. We discuss strategies such as the application of RTOS, careful server utilization management, and preventing queue overflows to maintain measure invariance and ergodicity in deployed systems. The insights gained from this investigation lead to the development of four software engineering design rules essential for ensuring BET-compliance in software systems. This seminar provides a deep understanding of ergodicity in software systems, equipping attendees with the knowledge to address related challenges in their own work.