Special Topics in Software Engineering:

Java HotSpot VM

Overview

This course will give an overview of Oracle's Java HotSpot VM, which is among the best-performing Java virtual machines.The focus will be on the internal data structures, the just-in-time compiler, and garbage collection.

Additionally, the Graal research project will be presented. The course will also show how to use the available visualization tools. This includes c1visualizer and IdealGraphVisualizer to analyze the compilation strategies of the two virtual machines. Further we will present some of the available tools to analyze garbage collection issues and performance (Logs, JConsole, JMap, MemoryAnalyzer).

There will be no exam, the participants will have to build the VM on their own computer and implement a small modification to HotSpot.

Keywords

• Virtual machine architecture: Object layout, interpreter, garbage collector, ...
• Compiler optimizations: SSA-form, intermediate representations, global value numbering, register allocation, canonicalization, loop unrolling, ...
• Generated code: Stack frames, stack banging, safepoints, memory performance, ...
Garbage Collection: TLABs and PLABs, large objects, generational setup (Young, Tenured, Permanent generation), available collection algorithms (Serial GC, CMS and Garbage-First), evaluating collectors, ...

Dates

Online Resources

• The OpenJDK project
• List of scientific publications of our institute in this area
• HotSpot Internals Wiki
• Client compiler visualization: c1visualizer
• Graal project
• Server compiler visualization: IdealGraphVisualizer