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Interactive Terminal UI (TUI) Dashboard

Helix features a terminal dashboard built with Lanterna that visualizes runtime HotSpot JVM metrics and cache health without leaving the terminal.

Launching the Dashboard​

./scripts/start-helix.sh profile --tui

Dashboard Layout & Grid Components​

+-----------------------------------------------------------------------------------------+
| HELIX JVM SCRIPTING ENGINE - LIVE DASHBOARD                                    [Ctrl+C] |
+-----------------------------------------------------------------------------------------+
| SYSTEM HEALTH               | JVM MEMORY & GC             | TIERED CACHE TELEMETRY      |
| --------------------------- | --------------------------- | --------------------------- |
| Status:       HEALTHY       | Heap Used:    245 MB / 4 GB | L1 Strong Hits:  1,420,500  |
| Uptime:       01h 24m 12s   | Metaspace:    38.4 MB       | L2 Soft Hits:    14,200     |
| Threads:      18 active     | GC Pause:     1.8 ms avg    | L3 Weak Hits:    420        |
| CPU Usage:    14.2%         | Alloc Rate:   8.5 MB/s      | Total Misses:    12         |
+-----------------------------------------------------------------------------------------+
| JIT COMPILATION METRICS     | RECENT EVENT LOGS                                         |
| --------------------------- | --------------------------------------------------------- |
| Compiled Methods: 412       | [14:20:01] Compiled FraudDetectionRule_v1 (ASM: 1.8ms)   |
| Tier 4 (C2) Hot:  89        | [14:20:15] Executed batch scenario (10,000 items)         |
| Inlined Methods:  310       | [14:20:30] SoftReference sweep cleared 0 entries          |
+-----------------------------------------------------------------------------------------+
| ACTIONS: [ [F1] Trigger GC ]  [ [F2] Invalidate L1 ]  [ [F3] Dump JFR ]  [ [F] Flame Graph ]  [ [Q] Quit ] |
+-----------------------------------------------------------------------------------------+

Key Interactive Controls​

  • F1 / [Trigger GC]: Triggers an explicit Garbage Collection pass and recalculates Metaspace reclamation.
  • F2 / [Invalidate L1]: Flushes Tier 1 Caffeine cache to observe L2/L3 promotion mechanics.
  • F3 / [Dump JFR]: Captures an immediate 60-second JDK Flight Recorder snapshot to disk.
  • F / [Flame Graph]: Toggles the full-screen interactive Unicode ASCII Flame Graph browser.
  • Q / Ctrl+C: Gracefully closes active executors, flushes metrics, and exits the dashboard.

Interactive Flame Graph Browser ([F])​

Pressing F transitions the dashboard into the interactive Lanterna flame graph explorer (FlameGraphPanel):

┌─ HELIX JVM ENGINE - REAL-TIME PROFILING & OBSERVABILITY ──────────────────────────┐
│                                                                                   │
│  [100.0%] com.helix.cli.HelixApplication.main                                     │
│  ├── [74.2%] com.helix.core.executor.VirtualThreadRuleExecutor.executeBatch       │
│  │   ├── [48.1%] com.helix.generated.FraudRule_v1.eval                           │
│  │   │   ├── [32.4%] com.helix.api.ExecutionContext.getInt                        │
│  │   │   └── [15.7%] com.helix.api.ExecutionContext.getString                     │
│  │   └── [26.1%] java.util.concurrent.StructuredTaskScope.join                    │
│  └── [25.8%] com.helix.core.RuleCompiler.compile                                  │
│                                                                                   │
├─ Frame Inspector & Telemetry ─────────────────────────────────────────────────────┤
│ Frame:    com.helix.generated.FraudRule_v1.eval                                   │
│ Total:    2,718 samples (48.1%) | Self: 0 (0.0%) | Depth: 3 | Children: 2         │
├───────────────────────────────────────────────────────────────────────────────────┤
│ [↑/↓] Select Frame  [Enter] Zoom In  [Backspace] Zoom Out  [/] Search  [E] Export  │
└───────────────────────────────────────────────────────────────────────────────────┘

Navigation & Exploration Controls:​

  • Up / Down Arrow Keys: Cycle through sibling and child stack frames. The selected frame is highlighted with high-contrast text.
  • Enter: Zoom into the currently selected frame, recalculating percentage widths relative to the new sub-root.
  • Backspace: Zoom out to the parent frame level.
  • / (Slash): Filter the tree by package, class, or method keyword (e.g. FraudRule).
  • E: Export the currently rendered view to an SVG vector flame graph or HTML flame graph under target/flamegraphs/.
  • Esc or F: Return back to the primary system telemetry dashboard.