Jing mujoco mac

[jca0]

patch to run mujoco as subprocess so viewer works on mac

[greptile-apps]

Greptile Overview

Greptile Summary

This PR implements a subprocess-based architecture for running MuJoCo simulations on macOS to enable the viewer, which doesn't work in the main process on macOS.

Key Changes:

• Added MujocoEngine that conditionally uses subprocess on macOS (sys.platform == "darwin") when not headless
• Implemented shared memory IPC system (ShmWriter/ShmReader) for bidirectional communication between main process and MuJoCo subprocess
• Created mujoco_process.py as subprocess entry point that runs the simulation loop and viewer
• Added XML parser to extract joint/actuator/tendon mappings from MuJoCo MJCF files
• Introduced simulation module framework with SimulationModule, SimManipInterface, and abstract SimulationEngine base
• Added comprehensive test coverage (unit and e2e tests)

Issues Found:

• Line 155 in sim_module.py uses msg.positions instead of msg.velocities for velocity commands (critical bug)

Confidence Score: 3/5

• PR has a critical bug in velocity command handling that will cause incorrect behavior
• Score reflects the presence of a critical syntax error on line 155 of sim_module.py where velocity commands incorrectly read from msg.positions instead of msg.velocities. This will cause all velocity commands to fail or behave incorrectly. The overall architecture is well-designed with proper shared memory synchronization, subprocess lifecycle management, and test coverage, but the bug must be fixed before merging.
• dimos/simulation/manipulators/sim_module.py requires immediate attention to fix the velocity command bug on line 155

Important Files Changed

Filename	Overview
dimos/simulation/engines/mujoco_engine.py	implemented dual-mode MuJoCo engine with subprocess support for macOS viewer, includes shared memory IPC and threading coordination
dimos/simulation/manipulators/mujoco_subprocess/shared_memory.py	implemented shared memory system for IPC between main process and MuJoCo subprocess, handles command/state synchronization
dimos/simulation/manipulators/mujoco_subprocess/mujoco_process.py	subprocess entry point for MuJoCo simulation, reads commands from shared memory and executes simulation loop with viewer support
dimos/simulation/manipulators/sim_module.py	added simulation module with control/monitor loops, has velocity command handling issue on line 155
dimos/simulation/utils/xml_parser.py	added MuJoCo XML parser for extracting joint/actuator/tendon mappings from MJCF files

Sequence Diagram

sequenceDiagram
    participant User
    participant SimModule as SimulationModule
    participant SimInterface as SimManipInterface
    participant MujocoEngine
    participant ShmWriter
    participant Subprocess as MuJoCo Subprocess
    participant ShmReader
    participant MujocoSim as MuJoCo Simulation

    User->>SimModule: start()
    SimModule->>SimInterface: connect()
    SimInterface->>MujocoEngine: connect()
    
    alt macOS and not headless
        MujocoEngine->>ShmWriter: create shared memory
        MujocoEngine->>Subprocess: spawn (mjpython mujoco_process.py)
        Subprocess->>ShmReader: attach to shared memory
        Subprocess->>MujocoSim: initialize model and viewer
        Subprocess->>ShmReader: signal_ready()
        MujocoEngine->>ShmWriter: wait for is_ready()
        MujocoEngine-->>SimInterface: connected
    else Linux or headless
        MujocoEngine->>MujocoEngine: start sim_thread
        MujocoEngine-->>SimInterface: connected
    end
    
    SimInterface-->>SimModule: connected
    SimModule->>SimModule: start control_thread
    SimModule->>SimModule: start monitor_thread
    
    loop Control Loop (100Hz)
        User->>SimModule: publish JointCommand
        SimModule->>SimInterface: write_joint_positions()
        SimInterface->>MujocoEngine: write_joint_command()
        
        alt subprocess mode
            MujocoEngine->>ShmWriter: write_command()
            ShmWriter->>ShmWriter: increment seq[0]
            Subprocess->>ShmReader: read_command()
            ShmReader->>ShmReader: check seq[0]
            Subprocess->>MujocoSim: apply control
            MujocoSim->>MujocoSim: mj_step()
            Subprocess->>ShmReader: write_state()
            ShmReader->>ShmReader: increment seq[1]
            MujocoEngine->>ShmWriter: read_state()
        else threaded mode
            MujocoEngine->>MujocoEngine: update targets (with lock)
            MujocoEngine->>MujocoSim: apply_control()
            MujocoSim->>MujocoSim: mj_step()
            MujocoEngine->>MujocoEngine: update_joint_state()
        end
        
        MujocoEngine-->>SimInterface: joint state
        SimInterface-->>SimModule: positions, velocities, efforts
        SimModule->>User: publish JointState
    end
    
    User->>SimModule: stop()
    SimModule->>SimInterface: disconnect()
    SimInterface->>MujocoEngine: disconnect()
    
    alt subprocess mode
        MujocoEngine->>ShmWriter: signal_stop()
        Subprocess->>ShmReader: should_stop() == true
        Subprocess->>Subprocess: exit
        MujocoEngine->>Subprocess: terminate/kill
        MujocoEngine->>ShmWriter: cleanup()
    else threaded mode
        MujocoEngine->>MujocoEngine: stop_event.set()
        MujocoEngine->>MujocoEngine: join sim_thread
    end

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[greptile-apps]

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[greptile-apps]

uses msg.positions instead of msg.velocities for velocity command

Suggested change

	self._pending_velocities = list(msg.positions)
	self._pending_velocities = list(msg.velocities)