WASM 3.0: garbage collection, threads, and more | Andreas Rossberg | PodRocket

Andreas Rossberg unpacks WASM 3.0, covering new capabilities like garbage collection, exception handling, tail calls, and support for 64-bit addressing with multiple memories. The discussion explores deterministic profiles following relaxed sim, WebAssembly’s capability-based security model, and advances in sandboxing and module design. Andreas connects these features to practical use cases in JavaScript engines and applications like Google Sheets, then looks ahead to experimental work on threading, stack switching, and async programming models shaping the next phase of the WebAssembly ecosystem. -- Links Website: https://people.mpi-sws.org/~rossberg GitHub: https://github.com/rossberg Related resources WASM 3.0 Completed: https://webassembly.org/news/2025-09-... --- Fill out our feedback form to help us improve PodRocket! https://forms.gle/xHm5PdAasfYqXYzT7 --- Chapters 00:00 Intro: Welcome to PodRocket + Introducing Andreas Rossberg 01:00 From WebAssembly 2.0 to 3.0 — What’s New and Why It Matters 02:40 Garbage Collection and Unlocking Managed Languages 04:00 WebAssembly as a Universal Compilation Target 05:20 Adoption Curve and Ecosystem Growth 06:20 Expanding Address Space to 64-bit — Who Needs It and Why 08:00 WebAssembly Beyond the Web: Databases, LLMs, and Portability 09:00 Lessons from the JVM and .NET — A Truly Language-Neutral Platform 10:00 Sandboxing, Imports, and WebAssembly’s Security Model 12:00 Static Analysis, Capabilities, and Reducing Attack Surfaces 13:00 Multi-Memory Support: Security, Modularity, and Tooling 15:00 Features for Toolchains vs. Language Authors 17:00 Tail Calls, Functional Languages, and Hidden Runtime Benefits 18:40 Tables: Function References, Security, and Code Indirection 21:00 How Tables Enable Safe Function Pointers and Optimization 22:00 Exception Handling — Closing a Long-Standing Gap 23:30 Efficiency, Control Flow, and Language Design Differences 25:00 Deterministic Execution Profiles and Blockchain Use Cases 27:20 SIMD, Relaxed Semantics, and Hardware Divergence 29:30 Balancing Portability, Performance, and Philosophy 31:00 What WebAssembly Should Be: Principles and Compromises 32:00 Rejecting JavaScript-Specific Features (Strings Example) 33:40 Who Drives New Proposals — Implementers and Big Users 35:00 The Role of Browser Vendors in Standardization 36:00 Early Adoption: GC, Sheets, and Real-World Deployment 38:00 The Road Ahead — Threads, Stack Switching, and Beyond 40:00 Coroutines, Async/Await, and Control Abstractions 42:00 Language Benefits of Stack Switching 44:00 What’s Next for WebAssembly: Smaller Additions and Big Goals 45:00 How to Get Involved: The WebAssembly Community Group 46:00 Where Producers and Implementers Meet (or Don’t) 47:00 Closing Thoughts and Thanks --- 🎙 Listen to PodRocket 🎧 Spotify: https://open.spotify.com/show/6oFuKu8... 🎧 Apple Podcasts: https://podcasts.apple.com/us/podcast... 📺 Subscribe on YouTube: @LogRocket Follow on Socials ➡️ Noel Minchow, Host: linkedin.com/in/noel-minchow ➡️ Elizabeth Becz, Producer:   / elizabethb3cz   ➡️ LogRocket:   / logrocket   --- What does LogRocket do? LogRocket provides AI-first session replay and analytics that surface the UX and technical issues impacting user experiences. Start understanding where your users are struggling by trying it for free at LogRocket.com.