Valhalla - Where Are We?
summary
Project Valhalla delivers concrete features: an EA build of value classes that add a single modifier, a verifier-backed strict initialization rule, and proposed null-restricted types with tightened definite-assignment. Microbenchmarks show dramatic wins (matrix multiply ~6× throughput, arrays-of-pairs 3×–12×, immutable accumulation ~8×), and the VM avoids new bytecodes or type descriptors to improve migration compatibility. Remaining work: serialization compatibility, memory-model tearing for >64-bit flattened values (opt-in relaxed atomicity proposed), and follow-on JEPs for boxing and generics.
AI-written summary · about
chapters (9)
- 0:00Executive Summary
- 7:19Brief History
- 15:26Value Classes ⟪~⟫ Object Identity
- 24:03Null-Restricted Types ⟪~⟫ Nullability
- 31:53Strict Initialization
- 35:06The Cascade of Simplification
- 40:19Serialization
- 41:13Flattening & Tearing Values
- 47:10Mopping up
