HarmonyOS Flutter: Thread Analysis

HarmonyOS Flutter: Thread Analysis

Thread Execution Order

To analyze Flutter performance using trace tools:

1. Collect threads: Capture all threads during app runtime.

Sort by sequence

: Arrange threads in the order shown below (numbers indicate priority).

• 1️⃣ VSyncGennerator
• 2️⃣ DVSync-app
• 3️⃣ mmi_service
• 4️⃣ Application Main Thread
• 5️⃣ flutter.PointerEvent
• 6️⃣ 1.ui
• 7️⃣ 1.raster
• 8️⃣ DVSync-rs
• 9️⃣ RenderService
• 🔟 RSUniRenderThread
• ⚙️ RSHardwareThread
• 🔄 dpu_gfx_primary

https://p.ipic.vip/2ueyv5.png
After collection, threads appear in reverse order (top → bottom):
https://p.ipic.vip/pumt1l.png
https://p.ipic.vip/5v10cw.png
https://p.ipic.vip/0rz887.png

---

Thread Descriptions

1. VSyncGennerator
   • Generates software VSync signals to track frame timing.
2. DVSync-app
   • Delivers software VSync signals to the Flutter app.
3. mmi_service
   • Handles multi-modal input events (e.g., touch gestures).
4. Application Main Thread
   • Main thread of the OS process (name/process ID match).
   • Runs plugin code and platform-dependent logic.
5. flutter.PointerEvent
   • Transfers touch events from the Flutter engine to the UI thread (may not always exist).
6. 1.ui (UI Thread)
   • Executes Dart code in the Dart VM.
   • Builds the Layer Tree (device-independent rendering commands).
   • Critical: Avoid blocking this thread!
7. 1.raster (Raster Thread)
   • Converts the Layer Tree into GPU-renderable commands.
   • Runs Skia graphics library (CPU-bound, but impacts GPU performance).
8. DVSync-rs
   • Provides VSync signals to the Render Service (RS) process.
9. RenderService (RSUniRenderThread)
   • Primary thread for RS rendering pipeline.
10. RSHardwareThread
    • Final stage of RS rendering before hardware submission.
11. dpu_gfx_primary
    • Hardware-accelerated DPU (Display Processing Unit) signal.

---

Key Takeaways

• Performance Optimization: Focus on minimizing work on the UI Thread (1.ui) and optimizing rasterization (1.raster).
• Frame Drops: Investigate delays in DVSync-app, mmi_service, or GPU-related threads (e.g., dpu_gfx_primary).
• Tooling: Use trace analysis tools to visualize thread activity and identify bottlenecks.

Let me know if you need further refinements!