Guard kriging() against unbounded memory allocations (#1307)#1309
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kriging() takes an arbitrary point count N and template grid size with no upper bound. Three eager allocations scale with these inputs: - np.triu_indices(N) in _experimental_variogram (O(N^2) int64 pairs) - the (N+1) x (N+1) kriging matrix and its inverse - the (grid_pixels, N+1) prediction matrix in _kriging_predict A caller passing 50k points or a 5000x5000 template silently triggers tens of GB of allocation before any guard. Add _check_kriging_memory() that estimates the worst case of these three and raises MemoryError when the estimate exceeds 80% of available memory (using xrspatial.zonal._available_memory_bytes, same pattern as balanced_allocation). The error message names which allocation drove the estimate so the user knows whether to reduce N or the grid size.
This was referenced Apr 29, 2026
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) The k-nearest path in `idw()` calls `cKDTree.query(query_pts, k=k)`, which returns a `(grid_pixels, k)` float64 distance array and an int64 index array. Peak allocation is `grid_pixels * k * 16` bytes before any IDW arithmetic runs. A 50000 x 50000 template with k=12 needs about 480 GB and OOMs the process with no message naming the inputs that caused it. Add `_check_idw_memory(grid_pixels, k)` and call it at the top of the public `idw()` entrypoint when k is set on a numpy-backed template. Dask templates dispatch `_idw_knearest_numpy` per chunk via `map_blocks`, so chunk size already bounds the per-chunk allocation; the guard skips dask paths to avoid refusing legitimate chunked workloads. GPU backends reject k early. Same shape as the kriging guard from #1309. Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: brendancol <433221+brendancol@users.noreply.github.com>
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Summary
kriging(). It estimates the worst case across the three large allocations (variogram pair arrays atN*(N-1)/2, the(N+1)x(N+1)kriging matrix, and the(grid_pixels, N+1)prediction matrix) and raisesMemoryErrorbefore any of them run.0.8 * _available_memory_bytes()threshold, helper imported fromxrspatial.zonal.Nor the template grid.TestKrigingMemoryGuardmonkeypatch_available_memory_bytesto a small number. Covers the prediction-matrix path, the kriging-matrix path, a small-input pass-through, and a direct unit test of the helper.Closes #1307
Test plan
pytest xrspatial/tests/test_interpolation.py(34 passed locally)