JVM Mechanical Sympathy & Experiments
Helix includes a dedicated research and verification harness (engine-experiments) designed to demonstrate, profile, and verify low-level JVM behavior under real-world pressure.
The 5 Core JVM Behavior Experiments
| Experiment Name | JVM Internals Tested | Key Metrics Observed |
|---|---|---|
jit | HotSpot Tiered Compilation (C1/C2) & Inlining | Compilation tier transitions (0 -> 3 -> 4), bytecode size inlining limits (35B / 325B) |
metaspace | Metaspace Growth vs ClassLoader GC Unloading | Native memory MB growth, ClassLoader reachability, memory reclamation |
gc | Soft vs Weak Reference Pressure | SoftReference heap survival vs immediate WeakReference minor GC sweeps |
safepoint | Stop-The-World (STW) Pauses & TTSP | Time-To-Safepoint (TTSP) delay, thread synchronization latency |
layout | Java Object Layout (JOL) Headers & OOPs | Mark Word (8B), Klass Pointer (4B), instance padding (8B boundary alignment) |
Running Experiments via CLI
You can execute any experiment scenario using the bundled helper script or CLI:
# Run specific experiment
./scripts/run-experiment.sh jit
./scripts/run-experiment.sh metaspace
./scripts/run-experiment.sh gc
./scripts/run-experiment.sh safepoint
./scripts/run-experiment.sh layout
# Or run all experiments consecutively
./scripts/run-experiment.sh all