Day 2 Keynote
summary
A new Ruby 3.2+ sampling profiler called Vernier records both wall-clock and allocation samples, plus GVL, ractor, thread states, GC activity and idle time; it ships as a CLI plus a single‑page web viewer based on the Firefox profiler. A Bundler run shows a hotspot where string split runs ~200,000 times causing ~890,000 allocations; avoiding those allocations cuts a measured slow path dramatically. Vernier uses a dedicated C thread to never miss samples and to keep profiling overhead low.
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chapters (9)
- 0:00Introduction
- 2:17Performance philosophy
- 9:54Introducing Vernier
- 17:18Profiling in practice
- 20:47Instrumentation techniques
- 27:48Tracing vs. sampling
- 33:29Gvl and threading
- 36:55Evolution of profilers
- 45:28Real-world application
