Java Memory Model
summary
Describes why the original Java memory model is broken and how JSR-133 replaces it with concrete guarantees: strengthened final semantics, well-defined volatile behavior implemented as a store fence after write and load fence before read, and synchronized semantics that force cache flushes. Shows how hardware (registers, L1/L3 caches, MESI protocol) and JVM optimizations caused divergent implementations, explains that JVMs were unified by the new model, and reports measured performance costs as negligible. Slides: http://goo.gl/KFEjWe
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chapters (8)
- 0:00Introduction to speakers
- 1:37What is memory consistency
- 4:49Hardware memory models
- 9:32Java Memory Model basics
- 13:07Old Java model flaws
- 15:47Volatile and final explained
- 18:04Why built-in model wins
- 20:08Model clash and performance
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