Profiling#

Kit has a built-in profiler and bundles Tracy with it — no downloads, no code to add.

Quick start#

set CARB_PROFILING_PYTHON=1&& .\_build\windows-x86_64\release\lightspeed.app.trex_dev.bat

No space before && — set VAR=1 && command would capture the trailing space into the variable value, which carb.profiler doesn’t read as enabled.

Inside the app:

  1. Press F8 to open the Profiler window.

  2. Tick CPU Profiler.

  3. Press F5 to start, drive the app, press F5 again to stop.

Traces land in _build\…\release\logs\Kit\RTX Remix Dev\<version>\traces\ as ct_<timestamp>.gz. Open them from the Profiler window’s Capture Browser (see Opening existing captures below).

Profile startup only#

One-shot capture: runs the app, writes a trace, quits, opens it in Tracy.

set CARB_PROFILING_PYTHON=1&& .\_build\windows-x86_64\release\kit\profile_startup.bat .\_build\windows-x86_64\release\apps\lightspeed.app.trex_dev.kit

The trace (startup_profile.gz) lands in the directory you ran the command from.

Live Tracy connection#

Watch the app in real time as you interact. Load both backends through the multiplexer:

set CARB_PROFILING_PYTHON=1&& .\_build\windows-x86_64\release\lightspeed.app.trex_dev.bat --/app/profilerBackend=[cpu,tracy]

Inside the app, press F8 to open the Profiler window and click Launch Tracy and Connect, then press F5 to start emitting events.

Use [cpu,tracy], not a bare tracy. The Profiler window crashes if the CPU backend isn’t loaded.

Finding your code in a trace#

Python frames appear with a (Python) suffix; Python-interpreter C-API calls with a (C) suffix. For example:

  • omni.flux.stage_manager.factory.items.StageManagerItem.parent (Python)

  • builtins.hasattr (C)

In Tracy, Ctrl+F searches zone names — type the function or class name and it jumps to every call site on every thread. Searching by zone is usually faster than scanning by thread, especially for async code: asyncio work dispatched through carb.tasking runs on pooled fibers labelled Fiber #N, and a single coroutine can execute across many of them.

Opening existing captures#

Press F8 to open the Profiler window, then click Browse to open the Captured Traces Browser. Each saved trace has a row of buttons — click tracy to open it in the bundled Tracy.

Note

Widen the Captured Traces Browser window if you don’t see the tracy button — on narrower widths the row’s buttons get clipped off the right side.

Each row also has unzip (extracts the .gz to a .json you can drop into chrome://tracing), stats, snakeviz (cProfile captures only), and remove if you need them.

References#