Replaces Isaac Sim SimulationManager with IsaacLab SimulationManager

[ooctipus]

Description

Adds simulation manager that replaces Isaac sim simulation manager,
this is currently a draft, things are mostly working, but lacks clean up.

[greptile-apps]

Greptile Overview

Greptile Summary

Replaces Isaac Sim's SimulationManager with a standalone IsaacLab implementation to provide better control over physics lifecycle, callbacks, and simulation views.

Key Changes

• New SimulationManager class (simulation_manager.py): Implements physics lifecycle management, callback registration, and simulation view creation using class-level singleton pattern
• SimulationContext refactored: No longer inherits from Isaac Sim's base class, now standalone with direct integration to the new SimulationManager
• Monkey-patching strategy: Runtime replacement of Isaac Sim's SimulationManager in __init__.py to ensure all code uses the new implementation
• Kit file changes: Disabled isaacsim.core.simulation_manager extension to prevent conflicts
• Widespread integration updates: Updated 64 files including assets, sensors, environments, and tests to use the new manager

Architecture

The new SimulationManager uses a class-level singleton pattern with lifecycle events (PHYSICS_WARMUP, PHYSICS_READY, POST_RESET, etc.) to coordinate initialization across assets and sensors. It manages simulation views for both torch and warp backends, handles timeline callbacks, and provides compatibility stubs for Isaac Sim APIs.

Potential Concerns

• Weakref handling in callback registration could cause silent failures if objects are garbage collected
• Monkey-patching at import time may not catch all cached references to the original class
• Class-level state reset in clear() doesn't reset _callback_id, which could cause ID conflicts in long-running sessions

Confidence Score: 3/5

• Safe to merge with minor risks related to callback lifecycle and monkey-patching timing
• Score reflects a significant architectural change with mostly working implementation, but several edge cases around callback management and initialization timing need attention. The weakref usage and monkey-patching strategy could cause subtle bugs in production
• Pay close attention to simulation_manager.py (callback registration) and __init__.py (monkey-patching timing)

Important Files Changed

Filename	Overview
source/isaaclab/isaaclab/sim/simulation_manager.py	New SimulationManager implementation replaces Isaac Sim's version, handles physics lifecycle, callbacks, and view creation
source/isaaclab/isaaclab/sim/simulation_context.py	Removed inheritance from Isaac Sim's SimulationContext, now standalone implementation integrating with new SimulationManager
source/isaaclab/isaaclab/sim/init.py	Added monkey-patching logic to replace Isaac Sim's SimulationManager with IsaacLab's implementation at runtime
source/isaaclab/isaaclab/assets/asset_base.py	Updated imports and callback handling to use new SimulationManager, changed event payload structure
source/isaaclab/isaaclab/sensors/sensor_base.py	Updated imports and callback handling to use new SimulationManager, removed backend property access
source/isaaclab/isaaclab/envs/manager_based_env.py	Removed extension mode checks and clear_all_callbacks() call, simplified initialization logic
apps/isaaclab.python.kit	Disabled Isaac Sim's isaacsim.core.simulation_manager extension to prevent conflicts

Sequence Diagram

sequenceDiagram
    participant User
    participant SimContext as SimulationContext
    participant SimMgr as SimulationManager
    participant Timeline
    participant PhysX
    participant Assets
    participant Sensors

    User->>SimContext: __init__(cfg)
    SimContext->>SimContext: Create stage
    SimContext->>SimMgr: initialize()
    SimMgr->>Timeline: Subscribe to PLAY/STOP events
    SimMgr->>SimMgr: Setup internal callbacks
    SimContext->>SimContext: Configure physics scene
    SimContext->>PhysX: Apply physics settings
    
    User->>SimContext: reset()
    SimContext->>Timeline: stop() then play()
    Timeline->>SimMgr: _on_play event
    SimMgr->>SimMgr: initialize_physics()
    SimMgr->>PhysX: force_load_physics_from_usd()
    SimMgr->>PhysX: start_simulation()
    SimMgr->>SimMgr: Dispatch PHYSICS_WARMUP event
    SimMgr->>SimMgr: _create_views()
    SimMgr->>PhysX: create_simulation_view(backend)
    SimMgr->>SimMgr: Dispatch SIMULATION_VIEW_CREATED
    SimMgr->>SimMgr: Dispatch PHYSICS_READY
    Assets->>SimMgr: Register callbacks (PHYSICS_READY)
    Sensors->>SimMgr: Register callbacks (PHYSICS_READY)
    Assets->>Assets: _initialize_impl()
    Sensors->>Sensors: _initialize_impl()
    
    User->>SimContext: step()
    SimContext->>PhysX: simulate(dt)
    PhysX->>SimMgr: PRE_PHYSICS_STEP callbacks
    PhysX->>PhysX: Physics update
    PhysX->>SimMgr: POST_PHYSICS_STEP callbacks
    SimContext->>SimContext: render()
    
    User->>SimContext: clear_instance()
    SimContext->>SimMgr: clear()
    SimMgr->>SimMgr: dispatch_prim_deletion("/")
    Assets->>Assets: _clear_callbacks()
    Sensors->>Sensors: _clear_callbacks()
    SimMgr->>SimMgr: Invalidate views
    SimMgr->>SimMgr: Clear all state
    SimContext->>PhysX: detach_stage()

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[greptile-apps]

_{7 files reviewed, 2 comments}

_{Edit Code Review Agent Settings | Greptile}

[greptile-apps]

Using weakref.proxy in a lambda can cause issues if the object is garbage collected before the callback is invoked

Suggested change

	if hasattr(callback, "__self__"):
	obj_ref = weakref.proxy(callback.__self__)
	method_name = callback.__name__
	cb = lambda e, o=obj_ref, m=method_name: getattr(o, m)(e)
	if hasattr(callback, "__self__"):
	obj_ref = weakref.ref(callback.__self__)
	method_name = callback.__name__
	def cb(e):
	obj = obj_ref()
	if obj is not None:
	getattr(obj, method_name)(e)

[greptile-apps]

Verify that monkey-patching occurs before any Isaac Sim code caches references to the original SimulationManager class, otherwise those references will still point to the old implementation