sensible job count

Tools/python/split_layers.py

@@ -129,8 +129,8 @@ def generate_gds_file(layout_path,cellname):
 		cell=cell.add(gdspy.Rectangle(p11, p12, 1))
 		cell=cell.add(gdspy.Rectangle(p21, p22, 1))
 		cell=cell.flatten()
-		num_cores = multiprocessing.cpu_count() - 2
-		Parallel(n_jobs=num_cores, verbose=50)(delayed(split_task)(p11,p12,p21,p22,cell,layername)for layername in layer_mapping)
+		num_cores = multiprocessing.cpu_count()
+		Parallel(n_jobs=max(1,num_cores-2), verbose=50)(delayed(split_task)(p11,p12,p21,p22,cell,layername)for layername in layer_mapping)
 
 	except Exception as e:
 		print("Can't do this:"+e)