Fail if array created with asarray is greater than 1MB

cubed/storage/virtual.py

@@ -8,6 +8,7 @@
 from cubed.backend_array_api import namespace as nxp
 from cubed.backend_array_api import numpy_array_to_backend_array
 from cubed.types import T_DType, T_RegularChunks, T_Shape
+from cubed.utils import memory_repr
 
 
 class VirtualEmptyArray:
@@ -104,7 +105,12 @@ def __init__(
         self,
         array: np.ndarray,  # TODO: generalise
         chunks: T_RegularChunks,
+        max_nbytes: int = 10**6,
     ):
+        if array.nbytes > max_nbytes:
+            raise ValueError(
+                f"Size of in memory array is {memory_repr(array.nbytes)} which exceeds maximum of {memory_repr(max_nbytes)}. Consider loading the array from storage using `from_array`."
+            )
         self.array = array
         # use an in-memory Zarr array as a template since it normalizes its properties
         # and is needed for oindex

cubed/tests/test_core.py

@@ -40,6 +40,15 @@ def modal_executor(request):
     return request.param
 
 
+def test_as_array_fails(spec):
+    a = np.ones((1000, 1000))
+    with pytest.raises(
+        ValueError,
+        match="Size of in memory array is 8.0 MB which exceeds maximum of 1.0 MB.",
+    ):
+        xp.asarray(a, chunks=(100, 100), spec=spec)
+
+
 def test_regular_chunks(spec):
     xp.ones((5, 5), chunks=((2, 2, 1), (5,)), spec=spec)
     with pytest.raises(ValueError):