SE Radio 685: Will Wilson on Deterministic Simulation Testing
Software Engineering Radio - the podcast for professional software developers
Release Date: 09/10/2025
Software Engineering Radio - the podcast for professional software developers
Yechezkel "Chez" Rabinovich, CTO and co-founder at Groundcover, joins SE Radio host to discuss the key challenges in migrating observability toolsets. The episode starts with a look at why customers might seek to migrate their existing Observability stack, and then Chez explains some approaches and techniques for doing so. The discussion turns to OpenTelemetry, including what it is and how Groundcover helps with the migration of dashboards, monitors, pipelines, and integrations that are proprietary to vendor products. Chez describes methods for validating a successful migration, as well as...
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Murat Erder, CTO for Financial Services at Valtech in Europe, and Eoin Woods, independent consultant in the field of software architecture, join host Giovanni Asproni to talk about Continuous Architecture—an approach to software design where architectural decisions are made and refined continuously throughout the lifecycle of a system, instead of up front in a big design phase. The show starts with a definition of Continuous Architecture and a description of the six principles underpinning it. Following that is an explanation of the main reasons and advantages of this approach, which...
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Sriram Panyam returns to the show to discuss the system design interview (SDI) with host Robert Blumen. This challenging part of the hiring process is included in the interview loop for many jobs across tech, including management and for all levels from entry to senior. The conversation starts with a look at what the SDI is, who will face it, and how critical this interview is for hiring and leveling. Sriram shares some common system design questions and what the interviewers are generally looking for, including stated versus unstated requirements and ambiguity in the questions. He offers...
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In this episode, Sahaj Garg, CTO of wispr.ai, joins SE Radio host Robert Blumen to talk about the challenges of building low-latency AI applications. They discuss latency’s effect on consumer behavior as well as interactive applications. The conversation explores how to measure latency and how scale impacts it. Then Sahaj and Robert shift to themes around AI, including whether “AI” means LLMs or something broader, as they look at latency requirements and challenges around subtypes of AI applications. The final part of the episode explores techniques for managing latency in AI: speed vs...
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Derick Schaefer, author of CLI: A Practical Guide to Creating Modern Command-Line Interfaces, talks with host Robert Blumen about command-line interfaces old and new. Starting with a short review of the origin of commands in the early unix systems, they trace the evolution of commands into modern CLIs. Following the historic rise, fall, and re-emergence of CLIs, they consider innovative examples such as git, github, WordPress, and warp. Schaefer clarifies whether commands are the same as CLIs and then discusses a range of topics, including implementation languages, packages in the golang...
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Max Geurnsey III and Luniel de Beer, co-authors of the book Ready: Why Most Software Projects Fail and How to Fix It, discuss the concept of readiness in software engineering with host . Although Agile workflows and technical practices help delivery, many software efforts still struggle to achieve desired outcomes. Rework, shifting requirements, delays, defects, and mounting technical debt can plague software delivery and impede or altogether halt progress toward goals. The problem is often that implementation begins prematurely, before the team is properly set up for...
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Mojtaba Sarooghi, a Distinguished Product Architect at Queue-it, speaks with host Jeremy Jung about virtual waiting rooms for high-traffic events such as concerts and limited-quantity product releases. They explore using a virtual queue to prevent overloading systems, how most traffic is from bots, using edge workers to reduce requests to the customer's origin servers, and strategies for detecting bots in cooperation with vendors. Mojtaba discusses using AWS services like Elastic Load Balancing, DynamoDB, and Simple Notification Service, and explains why DynamoDB's eventual consistency is a...
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In this episode, Benjamin Brial, CEO and co-founder of Cycloid, speaks with host Sriram Panyam about internal developer platforms (IDPs) and internal developer portals. The conversation explores how these platforms address the growing challenges of DevOps scalability, multi-cloud complexity, and cloud waste, all of which organizations face as they grow. Benjamin begins by framing the core problems that IDPs solve: DevOps struggling to scale beyond small teams, the complexity of managing hybrid environments across on-premises, public cloud, and private cloud infrastructure, and the significant...
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In this episode of Software Engineering Radio, Srujana Merugu, an AI researcher with decades of experience, speaks with host Priyanka Raghavan about building LLM-based applications. The discussion begins by clarifying essential concepts like generative vs. predictive AI, pre-training vs. fine-tuning, and the transformer architecture that powers modern LLMs. Srujana explains diffusion models and vision transformers, highlighting how multimodal AI is reshaping content creation. The conversation then moves to practical aspects—where LLMs make sense, where they don’t, and a decision framework...
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Philip Kiely, software developer relations lead at Baseten, speaks with host Jeff Doolittle about multi-agent AI, emphasizing how to build AI-native software beyond simple ChatGPT wrappers. Kiely advocates for composing multiple models and agents that take action to achieve complex user goals, rather than just producing information. He explains the transition from off-the-shelf models to custom solutions, driven by needs for domain-specific quality, latency improvements, and economic sustainability, which introduces the engineering challenge of inference engineering. Kiely stresses that AI...
info_outlineIn this episode, Will Wilson, CEO and co-founder of Antithesis, explores Deterministic Simulation Testing (DST) with host Sriram Panyam. Wilson was part of the pioneering team at FoundationDB that developed this revolutionary testing approach, which was later acquired by Apple in 2015. After seeing that even sophisticated organizations lacked robust testing for distributed systems, Wilson co-founded Antithesis in 2018 to make DST commercially available.
Deterministic simulation testing runs software in a fully controlled, simulated environment in which all sources of non-determinism are eliminated or controlled. Unlike traditional testing or chaos engineering, DST operates in a separate environment from production, allowing for aggressive fault injection without risk to live systems. The key breakthrough is perfect reproducibility -- any bug found can be recreated exactly using the same random seed.
Antithesis built "The Determinator," a custom deterministic hypervisor that simulates entire software stacks including virtual hardware, networking, and time. The system can compress years of stress testing into shorter timeframes by running simulations faster than wall-clock time. All external interfaces that could introduce non-determinism (network calls, disk I/O, system time) are mocked or controlled by the simulator.
The approach has proven effective with major organizations including MongoDB, Palantir, and Ethereum. For Ethereum's critical "Merge" upgrade in 2022, Antithesis found and helped fix several serious bugs that could have been catastrophic for the live network. The platform typically finds bugs that traditional testing methods miss entirely -- such as those arising from rare race conditions, complex timing issues, and unexpected system interactions.
This episode is sponsored by Monday Dev