Contents

Preface

• Audience
• Documentation Accessibility
• Related Documents
• Conventions

1 Introduction

2 Ergonomics

• Garbage Collector, Heap, and Runtime Compiler Default Selections
• Behavior-Based Tuning
  • Maximum Pause Time Goal
  • Throughput Goal
  • Footprint Goal
• Tuning Strategy

3 Generations

• Performance Considerations
• Measurement

4 Sizing the Generations

• Total Heap
• The Young Generation
  • Survivor Space Sizing

5 Available Collectors

• Selecting a Collector

6 The Parallel Collector

• Generations
• Parallel Collector Ergonomics
  • Priority of Goals
  • Generation Size Adjustments
  • Default Heap Size
    • Client JVM Default Initial and Maximum Heap Sizes
    • Server JVM Default Initial and Maximum Heap Sizes
    • Specifying Initial and Maximum Heap Sizes
• Excessive GC Time and OutOfMemoryError
• Measurements

7 The Mostly Concurrent Collectors

• Overhead of Concurrency
• Additional References

8 Concurrent Mark Sweep (CMS) Collector

• Concurrent Mode Failure
• Excessive GC Time and OutOfMemoryError
• Floating Garbage
• Pauses
• Concurrent Phases
• Starting a Concurrent Collection Cycle
• Scheduling Pauses
• Incremental Mode
  • Command-Line Options
  • Recommended Options
  • Basic Troubleshooting
• Measurements

9 Garbage-First Garbage Collector

• Allocation (Evacuation) Failure
• Floating Garbage
• Pauses
• Card Tables and Concurrent Phases
• Starting a Concurrent Collection Cycle
• Pause Time Goal

10 Garbage-First Garbage Collector Tuning

• Garbage Collection Phases
• Young Garbage Collections
• Mixed Garbage Collections
• Phases of the Marking Cycle
• Important Defaults
• How to Unlock Experimental VM Flags
• Recommendations
• Overflow and Exhausted Log Messages
• Humongous Objects and Humongous Allocations

11 Other Considerations

• Finalization and Weak, Soft, and Phantom References
• Explicit Garbage Collection
• Soft References
• Class Metadata