Valhalla - Where Are We?
summary
Project Valhalla introduces value classes (no identity) and null‑restricted types (the bang) with JVM verifier and strict‑initialization checks, shipped as JEPs (401 et al.) and Early Access builds; the spec is stable about a year and implementation is underway. Local scalarization, optimized calling conventions and heap flattening deliver big wins (matrix work shows up to 6x throughput, other cases 3x–12x) while keeping language changes minimal—a few class bits, a field attribute and verifier rules.
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chapters (15)
- 0:00Project Valhalla introduction
- 2:06Memory layout challenges
- 5:15The primitive object rift
- 9:33Project goals and progress
- 12:24Impediments to flattening
- 17:03Value classes
- 22:08JEP 401 and migration
- 23:29Null-restricted types
- 29:36Strict initialization
- 33:26Performance results
- 37:15Design philosophy
- 40:28Serialization and summary
- 43:30Future work
- 45:41Specialized generics
- 47:46Q&A session
