speed up vtk out

- limit to single precision
- write in background

python/damask/_vtk.py

@@ -1,3 +1,4 @@
+import multiprocessing as mp
 from pathlib import Path
 
 import pandas as pd
@@ -157,8 +158,11 @@ class VTK:
 
         return VTK(geom)
 
-
-    def write(self,fname):
+    @staticmethod
+    def _write(writer):
+        """Wrapper for parallel writing."""
+        writer.Write()
+    def write(self,fname,parallel=True):
         """
         Write to file.
 
@@ -166,6 +170,8 @@ class VTK:
         ----------
         fname : str
             Filename for writing.
+        parallel : boolean, optional
+            Write data in parallel background process. Defaults to True.
 
         """
         if   isinstance(self.geom,vtk.vtkRectilinearGrid):
@@ -183,7 +189,10 @@ class VTK:
         writer.SetCompressorTypeToZLib()
         writer.SetDataModeToBinary()
         writer.SetInputData(self.geom)
-
+        if parallel:
+            mp_writer = mp.Process(target=self._write,args=(writer,))
+            mp_writer.start()
+        else:
             writer.Write()
 
 
@@ -195,14 +204,21 @@ class VTK:
         N_cells  = self.geom.GetNumberOfCells()
 
         if   isinstance(data,np.ndarray):
-            d = np_to_vtk(num_array=data.reshape(data.shape[0],-1),deep=True)
             if label is None:
                 raise ValueError('No label defined for numpy.ndarray')
+
+            if data.dtype in [np.float64, np.float128]:                                             # avoid large files
+                d = np_to_vtk(num_array=data.astype(np.float32).reshape(data.shape[0],-1),deep=True)
+            else:
+                d = np_to_vtk(num_array=data.reshape(data.shape[0],-1),deep=True)
             d.SetName(label)
+
             if   data.shape[0] == N_cells:
                 self.geom.GetCellData().AddArray(d)
             elif data.shape[0] == N_points:
                 self.geom.GetPointData().AddArray(d)
+            else:
+                raise ValueError(f'Invalid shape {data.shape[0]}')
         elif isinstance(data,pd.DataFrame):
             raise NotImplementedError('pd.DataFrame')
         elif isinstance(data,Table):

python/tests/test_VTK.py

@@ -1,4 +1,6 @@
 import os
+import filecmp
+import time
 
 import pytest
 import numpy as np
@@ -18,7 +20,7 @@ class TestVTK:
         origin = np.random.random(3)
         v = VTK.from_rectilinearGrid(grid,size,origin)
         string = v.__repr__()
-        v.write(os.path.join(tmp_path,'rectilinearGrid'))
+        v.write(os.path.join(tmp_path,'rectilinearGrid'),False)
         vtr = VTK.from_file(os.path.join(tmp_path,'rectilinearGrid.vtr'))
         with open(os.path.join(tmp_path,'rectilinearGrid.vtk'),'w') as f:
             f.write(string)
@@ -26,10 +28,10 @@ class TestVTK:
         assert(string == vtr.__repr__() == vtk.__repr__())
 
     def test_polyData(self,tmp_path):
-        points = np.random.rand(3,100)
+        points = np.random.rand(100,3)
         v = VTK.from_polyData(points)
         string = v.__repr__()
-        v.write(os.path.join(tmp_path,'polyData'))
+        v.write(os.path.join(tmp_path,'polyData'),False)
         vtp = VTK.from_file(os.path.join(tmp_path,'polyData.vtp'))
         with open(os.path.join(tmp_path,'polyData.vtk'),'w') as f:
             f.write(string)
@@ -48,13 +50,29 @@ class TestVTK:
         connectivity = np.random.choice(np.arange(n),n,False).reshape(-1,n)
         v = VTK.from_unstructuredGrid(nodes,connectivity,cell_type)
         string = v.__repr__()
-        v.write(os.path.join(tmp_path,'unstructuredGrid'))
+        v.write(os.path.join(tmp_path,'unstructuredGrid'),False)
         vtu = VTK.from_file(os.path.join(tmp_path,'unstructuredGrid.vtu'))
         with open(os.path.join(tmp_path,'unstructuredGrid.vtk'),'w') as f:
             f.write(string)
         vtk = VTK.from_file(os.path.join(tmp_path,'unstructuredGrid.vtk'),'unstructuredgrid')
         assert(string == vtu.__repr__() == vtk.__repr__())
 
+
+    def test_parallel_out(self,tmp_path):
+        points = np.random.rand(102,3)
+        v = VTK.from_polyData(points)
+        fname_s = os.path.join(tmp_path,'single.vtp')
+        fname_p = os.path.join(tmp_path,'parallel.vtp')
+        v.write(fname_s,False)
+        v.write(fname_p,True)
+        for i in range(10):
+            if os.path.isfile(fname_p) and filecmp.cmp(fname_s,fname_p):
+                assert(True)
+                return
+            time.sleep(.5)
+        assert(False)
+
+
     @pytest.mark.parametrize('name,dataset_type',[('this_file_does_not_exist.vtk', None),
                                                   ('this_file_does_not_exist.vtk','vtk'),
                                                   ('this_file_does_not_exist.vtx', None)])