Guard diffuse() against unbounded allocations and steps loop (#1267)#1268
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brendancol merged 1 commit intomainfrom Apr 26, 2026
Merged
Guard diffuse() against unbounded allocations and steps loop (#1267)#1268brendancol merged 1 commit intomainfrom
brendancol merged 1 commit intomainfrom
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- Add _check_memory / _check_gpu_memory helpers (cost_distance pattern, ~32 B/pixel budget) and call them from _diffuse_numpy / _diffuse_cupy before per-step buffers are allocated. - Defer the np.full alpha allocation: dask + scalar diffusivity now passes the scalar straight through, and the eager paths only build the full raster after the memory guard runs. - Teach _diffuse_dask_cupy to handle scalar alpha lazily via cp.full per chunk, mirroring _diffuse_dask_numpy. - Cap steps at _MAX_STEPS (100,000) so a single call cannot pin a CPU. - Add tests covering oversize raster -> MemoryError, scalar diffusivity on dask -> no full-raster np.full, dask scalar matches dask array, and steps above the cap -> ValueError.
This was referenced Apr 25, 2026
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Closes #1267.
Summary
_check_memory/_check_gpu_memory, cost_distance pattern, ~32 B/pixel) that fire before the eager numpy / cupy paths allocate per-step buffers.np.full(agg.shape, alpha)up front for scalar diffusivity. Dask paths now keep the scalar through to the per-chunk worker; eager paths only build the full alpha raster after the memory guard runs._diffuse_dask_cupyto handle scalar alpha lazily viacp.fullper chunk, matching_diffuse_dask_numpy.stepsat_MAX_STEPS = 100_000via_validate_scalar(max_val=...)so a single call can't pin a CPU forever.Test plan
MemoryError(with_available_memory_bytesmonkeypatched)np.full(agg.shape)steps=10**12raisesValueErrornp.fullruns on the oversize input