Code Coverage Instrumentation

on YouTube ↗50m

" summary

Builds a live JVM agent (Sky Bar, revok, ning, dogmatic MVC examples) that instruments bytecode to count exact line executions and shows counts over websockets. Uses per-method local counters plus try/finally to avoid billions of call sites, falls back to static post-dominator analysis (quadratic and slow), and binds counters at bootstrap with invokeDynamic to a LongAdder for fast concurrent updates. Explores thread-local buffer hacks to batch commits, accepts eventual correctness, and adds differential snapshots for exploratory and comparative coverage in production.

AI-written summary · about

" chapters (13)

1. 0:00Introduction
2. 0:15Legal Slide
3. 2:08Dec
4. 9:26Code Coverage
5. 35:09Skybar
6. 35:31Stack Map Frames
7. 36:22Java C Bug
8. 38:39Whats Next
9. 39:38exploratory coverage
10. 39:51dewpost
11. 41:04Comparative Coverage
12. 42:14Dead Code
13. 44:38More Questions

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