windtunnel_3d.py Example crashes on launch

[omarthewizard]

When trying to run the windtunnel example, the solver crashes when setting up the mesh_boundary_masker class with the following stack trace:

Simulation Configuration:
Grid size: 512 x 128 x 128
Backend: ComputeBackend.WARP
Velocity set: D3Q27
Precision policy: PrecisionPolicy.FP32FP32
Prescribed velocity: 0.02
Reynolds number: 50000.0
Max iterations: 100000

==================================================

Warp 1.6.0 initialized:
   CUDA Toolkit 12.8, Driver 12.7
   Devices:
     "cpu"      : "x86_64"
     "cuda:0"   : "NVIDIA GeForce RTX 3060" (12 GiB, sm_86, mempool enabled)
   Kernel cache:
     /home/omar/.cache/warp/1.6.0
registered bc RegularizedBC_8751980669715 with id 1
registered bc FullwayBounceBackBC_8751980669718 with id 2
registered bc ExtrapolationOutflowBC_8751944695298 with id 3
registered bc HalfwayBounceBackBC_8751944709877 with id 4
Module xlb.operator.equilibrium.quadratic_equilibrium 7e68aa5 load on device 'cuda:0' took 0.50 ms  (cached)
Module xlb.operator.boundary_masker.indices_boundary_masker 590d1e3 load on device 'cuda:0' took 0.46 ms  (cached)
Module xlb.operator.boundary_masker.mesh_boundary_masker 9a9d5e8 load on device 'cuda:0' took 0.10 ms  (cached)
Traceback (most recent call last):
  File "/home/omar/Thesis/00-warp/XLB/XLB/examples/cfd/windtunnel_3d.py", line 107, in <module>
    f_0, f_1, bc_mask, missing_mask = stepper.prepare_fields()
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/stepper/nse_stepper.py", line 86, in prepare_fields
    bc_mask, missing_mask = self._process_boundary_conditions(self.boundary_conditions, bc_mask, missing_mask)
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/stepper/nse_stepper.py", line 117, in _process_boundary_conditions
    bc_mask, missing_mask = mesh_masker(bc, bc_mask, missing_mask)
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/operator.py", line 74, in __call__
    raise Exception(f"Error captured for backend with key {key} for operator {self.__class__.__name__}: {error}\n {traceback_str}")
Exception: Error captured for backend with key ('MeshBoundaryMasker', <ComputeBackend.WARP: 2>, '(self, bc, bc_mask, missing_mask)') for operator MeshBoundaryMasker: Expecting value: line 1 column 1 (char 0)
 Traceback (most recent call last):
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/operator.py", line 64, in __call__
    result = backend_method(self, *args, **kwargs)
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/boundary_masker/mesh_boundary_masker.py", line 225, in warp_implementation
    wp.launch(
  File "/home/omar/Thesis/00-warp/XLB/env/lib/python3.10/site-packages/warp/context.py", line 5408, in launch
    module_exec = kernel.module.load(device, block_dim)
  File "/home/omar/Thesis/00-warp/XLB/env/lib/python3.10/site-packages/warp/context.py", line 2246, in load
    meta = json.load(meta_file)
  File "/usr/lib/python3.10/json/__init__.py", line 293, in load
    return loads(fp.read(),
  File "/usr/lib/python3.10/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.10/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.10/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

(env) omar@Stallion:~/Thesis/00-warp/XLB/XLB/examples$ python3 cfd/windtunnel_3d.py > output.txt
Traceback (most recent call last):
  File "/home/omar/Thesis/00-warp/XLB/XLB/examples/cfd/windtunnel_3d.py", line 107, in <module>
    f_0, f_1, bc_mask, missing_mask = stepper.prepare_fields()
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/stepper/nse_stepper.py", line 86, in prepare_fields
    bc_mask, missing_mask = self._process_boundary_conditions(self.boundary_conditions, bc_mask, missing_mask)
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/stepper/nse_stepper.py", line 117, in _process_boundary_conditions
    bc_mask, missing_mask = mesh_masker(bc, bc_mask, missing_mask)
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/operator.py", line 74, in __call__
    raise Exception(f"Error captured for backend with key {key} for operator {self.__class__.__name__}: {error}\n {traceback_str}")
Exception: Error captured for backend with key ('MeshBoundaryMasker', <ComputeBackend.WARP: 2>, '(self, bc, bc_mask, missing_mask)') for operator MeshBoundaryMasker: Expecting value: line 1 column 1 (char 0)
 Traceback (most recent call last):
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/operator.py", line 64, in __call__
    result = backend_method(self, *args, **kwargs)
  File "/home/omar/Thesis/00-warp/XLB/XLB/xlb/operator/boundary_masker/mesh_boundary_masker.py", line 225, in warp_implementation
    wp.launch(
  File "/home/omar/Thesis/00-warp/XLB/env/lib/python3.10/site-packages/warp/context.py", line 5408, in launch
    module_exec = kernel.module.load(device, block_dim)
  File "/home/omar/Thesis/00-warp/XLB/env/lib/python3.10/site-packages/warp/context.py", line 2246, in load
    meta = json.load(meta_file)
  File "/usr/lib/python3.10/json/__init__.py", line 293, in load
    return loads(fp.read(),
  File "/usr/lib/python3.10/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.10/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.10/json/decoder.py", line 355, in raw_decode
    raise JSONDecodeError("Expecting value", s, err.value) from None
json.decoder.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

I have tried different shaped meshes, including meshes from the DrivAer set.

[hsalehipour]

@omarthewizard , can you please add this to the beginning of your main function in the example: wp.clear_kernel_cache() . Sometimes mysterious errors appear if you change the code and don't recompile. The above command forces a recompilation of all Warp kernels. Let me know if the error persists.

[omarthewizard]

Error appears to be gone! Thanks for the fix.