Optimize Stage Creation

Optimize Stage Creation#

Isaac Lab supports two experimental features to speed-up stage creation: fabric cloning and stage in memory. These features are particularly effective for large-scale RL setups with thousands of environments.

What These Features Do#

Fabric Cloning

Clones environments using Fabric library (see USD Fabric USDRT Documentation)
Partially supported and enabled by default on some environments (see Limitations section for a list)

Stage in Memory

Constructs the stage in memory, rather than with a USD file, avoiding overhead from disk I/O
After stage creation, if rendering is required, the stage is attached to the USD context, returning to the default stage configuration
Not enabled by default

Usage Examples#

Fabric cloning can be toggled by setting the clone_in_fabric flag in the InteractiveSceneCfg configuration.

Using Fabric Cloning with a RL environment

# create environment configuration
env_cfg = CartpoleEnvCfg()
env_cfg.scene.clone_in_fabric = True
# setup RL environment
env = ManagerBasedRLEnv(cfg=env_cfg)

Stage in memory can be toggled by setting the create_stage_in_memory in the SimulationCfg configuration.

Using Stage in Memory with a RL environment

# create config and set flag
cfg = CartpoleEnvCfg()
cfg.scene.num_envs = 1024
cfg.sim.create_stage_in_memory = True
# create env with stage in memory
env = ManagerBasedRLEnv(cfg=cfg)

Note, if stage in memory is enabled without using an existing RL environment class, a few more steps are need. The stage creation steps should be wrapped in a with statement to set the stage context. If the stage needs to be attached, the attach_stage_to_usd_context function should be called after the stage is created.

Using Stage in Memory with a manual scene setup

# init simulation context with stage in memory
sim = SimulationContext(cfg=SimulationCfg(create_stage_in_memory=True))

# grab stage in memory and set stage context
stage_in_memory = sim.get_initial_stage()
with stage_utils.use_stage(stage_in_memory):
    # create cartpole scene
    scene_cfg = CartpoleSceneCfg(num_envs=1024)
    scene = InteractiveScene(scene_cfg)
    # attach stage to memory after stage is created
    sim_utils.attach_stage_to_usd_context()

sim.play()

Limitations#