Engine settings

The Engine owns all execution-time configuration. Construct one and assign it to a Simulation or Experiment:

from radcad import Engine, Backend

experiment.engine = Engine(
    backend=Backend.PATHOS,
    processes=4,
    deepcopy=True,
    drop_substeps=False,
    raise_exceptions=True,
)
result = experiment.run()

Options

Option	Type	Default	Description
backend	Backend	Backend.DEFAULT (= PATHOS)	Parallel-processing backend. The RADCAD_BACKEND environment variable, if set, takes precedence. See Choose a backend.
processes	int	cpu_count - 1 (min 1)	Number of worker processes to spawn.
raise_exceptions	bool	True	Raise on failure, or catch and return partial results plus exception metadata. See Handle exceptions.
deepcopy	bool	True	Deepcopy State Variables to prevent unintended mutation. Disable for speed. See Improve performance.
deepcopy_method	Callable	pickle-based	Method used for deepcopies. Defaults to Pickle dumps/loads for speed; supply copy.deepcopy for broader type support.
drop_substeps	bool	False	Keep only the final substep per timestep, saving memory and time.
simulation_execution	SimulationExecution	auto	A custom SimulationExecution instance/subclass. Overrides raise_exceptions, deepcopy, deepcopy_method, and drop_substeps.

Passing an unrecognised option raises an exception, so typos fail fast.

Environment variables

Variable	Effect
RADCAD_BACKEND	Overrides the backend option, e.g. RADCAD_BACKEND=SINGLE_PROCESS. Used in CI and required for Windows tests to avoid recursion-depth errors.

Customising the simulation loop

To change execution behaviour beyond the options above (for example, the deepcopy method, or any step of the loop), subclass SimulationExecution and assign it:

import copy
from radcad.core import SimulationExecution

class CustomSimulationExecution(SimulationExecution):
    @staticmethod
    def deepcopy_method(obj):
        return copy.deepcopy(obj)

experiment.engine.simulation_execution = CustomSimulationExecution

See Improve performance for the rationale.