Shenandoah - The Garbage Collector That Could

Explore the innovative Shenandoah garbage collector in this 56-minute Devoxx conference talk. Dive into the design choices, internal details, performance benefits, and trade-offs of this low-pause collector for large Java applications. Learn how Shenandoah addresses the challenge of moving objects without stopping the application, significantly reducing GC pauses. Gain insights into concurrent marking, heap structure, write barriers, read barriers, and footprint internals. Discover how Shenandoah compares to other garbage collectors and its potential impact on microservices. Presented by Aleksey Shipilev, an experienced Java performance expert from Red Hat, this talk provides a comprehensive introduction to Shenandoah and its role in improving the performance of large-scale Java applications.

Intro
Overview. Landscape
Overview: Heap Structure
Overview: Cycle
Concurrent Mark: Three-Color Abstraction Assign colors to the objects
Concurrent Mark: Mutator Problems
Concurrent Mark: Two Pauses
Concurrent Mark: Observations
Concurrent Copy: Stop The World
Concurrent Copy: Mutator Problems
Concurrent Copy: Brooks Pointers
Write Barriers: Motivation
Write Barriers: Slowpath
Write Barriers: GC Evacuation Code
Read Barriers: Motivation
Read Barriers: Implementation
Read Barriers: Observations
CMP: Observations
Overall: Observations
Intermezzo: Testing
Intermezzo: Pauses vs. LDS
Intermezzo: Perf vs. LDS
Advanced: Major Assumption
Footprint: Internals
Footprint: Microservice Example
Immediates: Obvious Shortcut
Partials: Heap Segregation
Partials: Serial/Parallel/CMS
Partials: G1
Partials: Shenandoah
Partials: Example
Conclusion: In Single Picture
Conclusion: Releases
Conclusion: In Single Paragraph