Known Issues

GPU VRAM leak in non-headless mode across environment reloads

When running without --headless (i.e., with the GUI viewport enabled), GPU VRAM usage grows each time an environment is created and destroyed. After cycling through enough scenes, this will eventually cause an out-of-memory crash.

Root cause: In GUI mode, the Omniverse Kit viewport creates a Hydra render product and associated GPU textures to display the scene. When env.close() is called, IsaacLab clears the SimulationContext singleton and deletes the ViewportCameraController, but the underlying Kit viewport and its Hydra render product persist across stage reloads. Each subsequent create_env() call triggers omni.usd.get_context().new_stage(), which allocates new Hydra scene delegates and GPU-side textures for the viewport without fully releasing the previous ones. This is an IsaacLab 2.2.0 / Omniverse Kit issue — the viewport lifecycle is not tied to the SimulationContext lifecycle.

In headless mode, the viewport context and window are never created (_viewport_context = None, _viewport_window = None), so there is no viewport render product to leak.

Workaround: Always use --headless when running multi-task evaluations that cycle through many environments. If you need the GUI for debugging, limit your run to a small number of scenes (roughly fewer than 10, depending on GPU VRAM and camera resolution).

Rendering artefacts

When a new environment is created and loaded, artefacts from the previous scene will remain and disappear slowly. This is an IsaacLab/RTX issue. Please refer to appropriate bug reporting for IsaacLab/Sim sources.

By using Isaac Sim/Lab recommended GPUs, this effect is rarely observed.

Example run on a 3090: