Fixes issue with asset deinitialization due to torch > 2.1 (#640)

# Description

Ever since we upgraded the torch version from 2.0.1 (in Isaac Sim
2023.1.1) to 2.2 (in Isaac Sim 4.0), we have seen some of the tests
(such as `test_articulation.py`) fail due to improper deinitialization
of the created class.

This MR fixes this issue by creating a dummy tensor inside the
`SimulationContext` in Isaac Lab. While this is a hack, it is effective
and helps alleviate the problem. It is hard to figure out the root cause
without really understanding what changed on the torch side.

Fixes #639

## Type of change

- Bug fix (non-breaking change which fixes an issue)
- This change requires a documentation update

## Checklist

- [x] I have run the [`pre-commit` checks](https://pre-commit.com/) with
`./isaaclab.sh --format`
- [ ] I have made corresponding changes to the documentation
- [x] My changes generate no new warnings
- [ ] I have added tests that prove my fix is effective or that my
feature works
- [ ] I have updated the changelog and the corresponding version in the
extension's `config/extension.toml` file
- [x] I have added my name to the `CONTRIBUTORS.md` or my name already
exists there

docker/container.sh

@@ -232,9 +232,9 @@ x11_cleanup() {
 }
 
 submit_job() {
-    
+
     echo "[INFO] Arguments passed to job script ${@}"
-    
+
     case $CLUSTER_JOB_SCHEDULER in
         "SLURM")
             CMD=sbatch

source/extensions/omni.isaac.lab/omni/isaac/lab/sim/simulation_context.py

@@ -7,6 +7,7 @@ import builtins
 import enum
 import numpy as np
 import sys
+import torch
 import traceback
 import weakref
 from collections.abc import Iterator
@@ -195,6 +196,12 @@ class SimulationContext(_SimulationContext):
         # note: we do it once here because it reads the VERSION file from disk and is not expected to change.
         self._isaacsim_version = get_version()
 
+        # create a tensor for gravity
+        # note: this line is needed to create a "tensor" in the device to avoid issues with torch 2.1 onwards.
+        #   the issue is with some heap memory corruption when torch tensor is created inside the asset class.
+        #   you can reproduce the issue by commenting out this line and running the test `test_articulation.py`.
+        self._gravity_tensor = torch.tensor(self.cfg.gravity, dtype=torch.float32, device=self.cfg.device)
+
         # add callback to deal the simulation app when simulation is stopped.
         # this is needed because physics views go invalid once we stop the simulation
         if not builtins.ISAAC_LAUNCHED_FROM_TERMINAL:

source/extensions/omni.isaac.lab/test/assets/test_articulation.py

@@ -52,6 +52,7 @@ class TestArticulation(unittest.TestCase):
         # stop simulation
         self.sim.stop()
         # clear the stage
+        self.sim.clear_all_callbacks()
         self.sim.clear_instance()
 
     """
@@ -75,8 +76,12 @@ class TestArticulation(unittest.TestCase):
 
         # Play sim
         self.sim.reset()
+
+        # Check that boundedness of articulation is correct
+        self.assertEqual(ctypes.c_long.from_address(id(robot)).value, 1)
+
         # Check if robot is initialized
-        self.assertTrue(robot._is_initialized)
+        self.assertTrue(robot.is_initialized)
         # Check that floating base
         self.assertFalse(robot.is_fixed_base)
         # Check buffers that exists and have correct shapes
@@ -114,8 +119,12 @@ class TestArticulation(unittest.TestCase):
 
         # Play sim
         self.sim.reset()
+
+        # Check that boundedness of articulation is correct
+        self.assertEqual(ctypes.c_long.from_address(id(robot)).value, 1)
+
         # Check if robot is initialized
-        self.assertTrue(robot._is_initialized)
+        self.assertTrue(robot.is_initialized)
         # Check that floating base
         self.assertFalse(robot.is_fixed_base)
         # Check buffers that exists and have correct shapes
@@ -153,8 +162,12 @@ class TestArticulation(unittest.TestCase):
 
         # Play sim
         self.sim.reset()
+
+        # Check that boundedness of articulation is correct
+        self.assertEqual(ctypes.c_long.from_address(id(robot)).value, 1)
+
         # Check if robot is initialized
-        self.assertTrue(robot._is_initialized)
+        self.assertTrue(robot.is_initialized)
         # Check that fixed base
         self.assertTrue(robot.is_fixed_base)
         # Check buffers that exists and have correct shapes
@@ -207,8 +220,12 @@ class TestArticulation(unittest.TestCase):
 
         # Play sim
         self.sim.reset()
+
+        # Check that boundedness of articulation is correct
+        self.assertEqual(ctypes.c_long.from_address(id(robot)).value, 1)
+
         # Check if robot is initialized
-        self.assertTrue(robot._is_initialized)
+        self.assertTrue(robot.is_initialized)
         # Check that fixed base
         self.assertTrue(robot.is_fixed_base)
         # Check buffers that exists and have correct shapes
@@ -247,8 +264,12 @@ class TestArticulation(unittest.TestCase):
 
         # Play sim
         self.sim.reset()
+
+        # Check that boundedness of articulation is correct
+        self.assertEqual(ctypes.c_long.from_address(id(robot)).value, 1)
+
         # Check if robot is initialized
-        self.assertTrue(robot._is_initialized)
+        self.assertTrue(robot.is_initialized)
         # Check that fixed base
         self.assertTrue(robot.is_fixed_base)
         # Check buffers that exists and have correct shapes
@@ -281,8 +302,12 @@ class TestArticulation(unittest.TestCase):
 
         # Play sim
         self.sim.reset()
+
+        # Check that boundedness of articulation is correct
+        self.assertEqual(ctypes.c_long.from_address(id(robot)).value, 1)
+
         # Check if robot is initialized
-        self.assertTrue(robot._is_initialized)
+        self.assertTrue(robot.is_initialized)
         # Check that floating base
         self.assertTrue(robot.is_fixed_base)
         # Check buffers that exists and have correct shapes
@@ -327,8 +352,12 @@ class TestArticulation(unittest.TestCase):
 
         # Play sim
         self.sim.reset()
+
+        # Check that boundedness of articulation is correct
+        self.assertEqual(ctypes.c_long.from_address(id(robot)).value, 1)
+
         # Check if robot is initialized
-        self.assertTrue(robot._is_initialized)
+        self.assertTrue(robot.is_initialized)
         # Check that fixed base
         self.assertFalse(robot.is_fixed_base)
         # Check buffers that exists and have correct shapes
@@ -372,7 +401,7 @@ class TestArticulation(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if robot is initialized
-        self.assertFalse(robot._is_initialized)
+        self.assertFalse(robot.is_initialized)
 
     def test_out_of_range_default_joint_vel(self):
         """Test that the default joint velocity from configuration is out of range."""
@@ -390,7 +419,7 @@ class TestArticulation(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if robot is initialized
-        self.assertFalse(robot._is_initialized)
+        self.assertFalse(robot.is_initialized)
 
     def test_external_force_on_single_body(self):
         """Test application of external force on the base of the robot."""

source/extensions/omni.isaac.lab/test/assets/test_rigid_object.py

@@ -102,7 +102,7 @@ class TestRigidObject(unittest.TestCase):
                         sim.reset()
 
                         # Check if object is initialized
-                        self.assertTrue(cube_object._is_initialized)
+                        self.assertTrue(cube_object.is_initialized)
                         self.assertEqual(len(cube_object.body_names), 1)
 
                         # Check buffers that exists and have correct shapes
@@ -133,7 +133,7 @@ class TestRigidObject(unittest.TestCase):
                         sim.reset()
 
                         # Check if object is initialized
-                        self.assertTrue(cube_object._is_initialized)
+                        self.assertTrue(cube_object.is_initialized)
                         self.assertEqual(len(cube_object.body_names), 1)
 
                         # Check buffers that exists and have correct shapes
@@ -166,7 +166,7 @@ class TestRigidObject(unittest.TestCase):
                         sim.reset()
 
                         # Check if object is initialized
-                        self.assertFalse(cube_object._is_initialized)
+                        self.assertFalse(cube_object.is_initialized)
 
     def test_external_force_on_single_body(self):
         """Test application of external force on the base of the object.

source/extensions/omni.isaac.lab/test/deps/isaacsim/check_ref_count.py

+# Copyright (c) 2022-2024, The Isaac Lab Project Developers.
+# All rights reserved.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+
+"""
+This script demonstrates reference count of the robot view in Isaac Sim.
+
+When we make a class instance, the reference count of the class instance should always be 1.
+However, in this script, the reference count of the robot view is 2 after the class is created.
+This causes a memory leak in the Isaac Sim simulator and the robot view is not garbage collected.
+
+The issue is observed with torch 2.2 and Isaac Sim 4.0. It works fine with torch 2.0.1 and Isaac Sim 2023.1.
+It can be resolved by uncommenting the line that creates a dummy tensor in the main function.
+
+To reproduce the issue, run this script and check the reference count of the robot view.
+
+For more details, please check: https://github.com/isaac-sim/IsaacLab/issues/639
+"""
+
+"""Launch Isaac Sim Simulator first."""
+
+
+import contextlib
+
+with contextlib.suppress(ModuleNotFoundError):
+    import isaacsim  # noqa: F401
+
+from omni.isaac.kit import SimulationApp
+
+# launch omniverse app
+simulation_app = SimulationApp({"headless": True})
+
+"""Rest everything follows."""
+
+import ctypes
+import gc
+import torch  # noqa: F401
+
+import carb
+
+try:
+    import omni.isaac.nucleus as nucleus_utils
+except ModuleNotFoundError:
+    import omni.isaac.core.utils.nucleus as nucleus_utils
+
+import omni.isaac.core.utils.prims as prim_utils
+from omni.isaac.core.articulations import ArticulationView
+from omni.isaac.core.simulation_context import SimulationContext
+from omni.isaac.core.utils.carb import set_carb_setting
+
+# check nucleus connection
+if nucleus_utils.get_assets_root_path() is None:
+    msg = (
+        "Unable to perform Nucleus login on Omniverse. Assets root path is not set.\n"
+        "\tPlease check: https://docs.omniverse.nvidia.com/app_isaacsim/app_isaacsim/overview.html#omniverse-nucleus"
+    )
+    carb.log_error(msg)
+    raise RuntimeError(msg)
+
+
+ISAAC_NUCLEUS_DIR = f"{nucleus_utils.get_assets_root_path()}/Isaac"
+"""Path to the `Isaac` directory on the NVIDIA Nucleus Server."""
+
+ISAACLAB_NUCLEUS_DIR = f"{ISAAC_NUCLEUS_DIR}/IsaacLab"
+"""Path to the `Isaac/IsaacLab` directory on the NVIDIA Nucleus Server."""
+
+
+"""
+Classes
+"""
+
+
+class AnymalArticulation:
+    """Anymal articulation class."""
+
+    def __init__(self):
+        """Initialize the Anymal articulation class."""
+        # resolve asset
+        usd_path = f"{ISAACLAB_NUCLEUS_DIR}/Robots/ANYbotics/ANYmal-C/anymal_c.usd"
+        # add asset
+        print("Loading robot from: ", usd_path)
+        prim_utils.create_prim("/World/Robot", usd_path=usd_path, translation=(0.0, 0.0, 0.6))
+
+        # Resolve robot prim paths
+        root_prim_path = "/World/Robot/base"
+        # Setup robot
+        self.view = ArticulationView(root_prim_path, name="ANYMAL")
+
+    def __del__(self):
+        """Delete the Anymal articulation class."""
+        print("Deleting the Anymal view.")
+        self.view = None
+
+    def initialize(self):
+        """Initialize the Anymal view."""
+        self.view.initialize()
+
+
+"""
+Main
+"""
+
+
+def main():
+    """Spawns the ANYmal robot and clones it using Isaac Sim Cloner API."""
+
+    # Load kit helper
+    sim = SimulationContext(physics_dt=0.005, rendering_dt=0.005, backend="torch", device="cuda:0")
+
+    # Enable hydra scene-graph instancing
+    # this is needed to visualize the scene when flatcache is enabled
+    set_carb_setting(sim._settings, "/persistent/omnihydra/useSceneGraphInstancing", True)
+
+    # Create a dummy tensor for testing
+    # Uncommenting the following line will yield a reference count of 1 for the robot (as desired)
+    # dummy_tensor = torch.zeros(1, device="cuda:0")
+
+    # Robot
+    robot = AnymalArticulation()
+
+    print("Reference count of the robot view: ", ctypes.c_long.from_address(id(robot)).value)
+    print("Referrers of the robot view: ", gc.get_referrers(robot))
+    print("---" * 10)
+
+    # Play the simulator
+    sim.reset()
+
+    print("Reference count of the robot view: ", ctypes.c_long.from_address(id(robot)).value)
+    print("Referrers of the robot view: ", gc.get_referrers(robot))
+    print("---" * 10)
+
+    robot.initialize()
+
+    print("Reference count of the robot view: ", ctypes.c_long.from_address(id(robot)).value)
+    print("Referrers of the robot view: ", gc.get_referrers(robot))
+    print("---" * 10)
+
+    # Stop the simulator
+    sim.stop()
+
+    print("Reference count of the robot view: ", ctypes.c_long.from_address(id(robot)).value)
+    print("Referrers of the robot view: ", gc.get_referrers(robot))
+    print("---" * 10)
+
+    # Clean up
+    sim.clear()
+
+    print("Reference count of the robot view: ", ctypes.c_long.from_address(id(robot)).value)
+    print("Referrers of the robot view: ", gc.get_referrers(robot))
+    print("---" * 10)
+
+
+if __name__ == "__main__":
+    # run the main function
+    main()
+    # close sim app
+    simulation_app.close()

source/extensions/omni.isaac.lab/test/sensors/test_camera.py

@@ -94,7 +94,7 @@ class TestCamera(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if camera is initialized
-        self.assertTrue(camera._is_initialized)
+        self.assertTrue(camera.is_initialized)
         # Check if camera prim is set correctly and that it is a camera prim
         self.assertEqual(camera._sensor_prims[0].GetPath().pathString, self.camera_cfg.prim_path)
         self.assertIsInstance(camera._sensor_prims[0], UsdGeom.Camera)

source/extensions/omni.isaac.lab/test/sensors/test_ray_caster_camera.py

@@ -106,7 +106,7 @@ class TestWarpCamera(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if camera is initialized
-        self.assertTrue(camera._is_initialized)
+        self.assertTrue(camera.is_initialized)
         # Simulate for a few steps
         # note: This is a workaround to ensure that the textures are loaded.
         #   Check "Known Issues" section in the documentation for more details.

source/extensions/omni.isaac.lab/test/sensors/test_tiled_camera.py

@@ -84,7 +84,7 @@ class TestTiledCamera(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if camera is initialized
-        self.assertTrue(camera._is_initialized)
+        self.assertTrue(camera.is_initialized)
         # Check if camera prim is set correctly and that it is a camera prim
         self.assertEqual(camera._sensor_prims[0].GetPath().pathString, self.camera_cfg.prim_path)
         self.assertIsInstance(camera._sensor_prims[0], UsdGeom.Camera)
@@ -133,7 +133,7 @@ class TestTiledCamera(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if camera is initialized
-        self.assertTrue(camera._is_initialized)
+        self.assertTrue(camera.is_initialized)
         # Check if camera prim is set correctly and that it is a camera prim
         self.assertEqual(camera._sensor_prims[1].GetPath().pathString, "/World/Origin_01/CameraSensor")
         self.assertIsInstance(camera._sensor_prims[0], UsdGeom.Camera)
@@ -184,7 +184,7 @@ class TestTiledCamera(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if camera is initialized
-        self.assertTrue(camera._is_initialized)
+        self.assertTrue(camera.is_initialized)
         # Check if camera prim is set correctly and that it is a camera prim
         self.assertEqual(camera._sensor_prims[1].GetPath().pathString, "/World/Origin_01/CameraSensor")
         self.assertIsInstance(camera._sensor_prims[0], UsdGeom.Camera)
@@ -232,7 +232,7 @@ class TestTiledCamera(unittest.TestCase):
         # Play sim
         self.sim.reset()
         # Check if camera is initialized
-        self.assertTrue(camera._is_initialized)
+        self.assertTrue(camera.is_initialized)
         # Check if camera prim is set correctly and that it is a camera prim
         self.assertEqual(camera._sensor_prims[1].GetPath().pathString, "/World/Origin_01/CameraSensor")
         self.assertIsInstance(camera._sensor_prims[0], UsdGeom.Camera)

source/extensions/omni.isaac.lab_assets/test/test_valid_configs.py

@@ -64,7 +64,7 @@ class TestValidEntitiesConfigs(unittest.TestCase):
                         sim.reset()
 
                         # check asset is initialized successfully
-                        self.assertTrue(entity._is_initialized)
+                        self.assertTrue(entity.is_initialized)
 
 
 if __name__ == "__main__":