add warning when coordinates data equals half system memory #50

Author: logicabrity

fidimag/common/cuboid_mesh.py

@@ -26,6 +26,7 @@
 in the innermost loop, and the z-axis in the outermost loop!
 
 """
+import os
 import numpy as np
 from textwrap import dedent
 from six.moves import range
@@ -69,6 +70,7 @@ def __init__(self, dx=1, dy=1, dz=1, nx=1, ny=1, nz=1, x0=0, y0=0, z0=0,
         self.n = nx * ny * nz  # total number of cells
         self.nxy = nx * ny  # number of cells in the x-y plane
         self.size = (nx, ny, nz)
+        self.check_size()
 
         self.mesh_type = "cuboid"
         self.unit_length = unit_length
@@ -258,3 +260,25 @@ def vertices(self, origin=(0, 0, 0)):
                     grid[i] = (x, y, z)
                     i += 1
         return grid
+
+    def check_size(self, system_memory_fake_for_testing=None):
+        """
+        Provide an estimate of how much system memory is needed and warn accordingly.
+
+        """
+        bytes_per_float_numpy = 8
+        size_coordinates_bytes = self.nx * self.ny * self.nz * 3 * bytes_per_float_numpy
+        size_coordinates_GiB = size_coordinates_bytes / (1024. ** 3)
+
+        if system_memory_fake_for_testing is None:
+            mem_bytes = os.sysconf('SC_PAGE_SIZE') * os.sysconf('SC_PHYS_PAGES')
+            mem_GiB = mem_bytes / (1024. ** 3)
+        else:
+            mem_GiB = system_memory_fake_for_testing
+
+        if 2 * size_coordinates_GiB > mem_GiB:
+            # print because no logging yet
+            print "Warning! Size of mesh coordinates i {} GiB.".format(size_coordinates_GiB)
+            print "You have {} GiB system memory. Possible halt.".format(mem_GiB)
+            return 1
+        return 0

fidimag/common/cuboid_mesh_test.py

@@ -242,3 +242,8 @@ def test_vector_field_shape():
     expected_shape_for_vector_field = (expected_nb_cells, 3)
     assert mesh.vector_shape() == expected_shape_for_vector_field
     m = np.zeros(mesh.vector_shape())  # usage example
+
+
+def test_check_size():
+    mesh = CuboidMesh(1, 1, 1, 2, 3, 4)
+    assert 1 == mesh.check_size(system_memory_fake_for_testing=0)