Compile programs even for single device

model.py

@@ -347,25 +347,25 @@ class StaticGraphAdapter(object):
                 startup_prog = self._startup_prog._prune(uninitialized)
                 self._executor.run(startup_prog)
 
-        if len(device_ids) < 2:
-            return prog
-
-        share_vars_from = None
-        if self.mode == 'eval' and 'train' in self._compiled_progs:
-            share_vars_from = self._compiled_progs['train']
-        # HACK invalidate eval program if is compiled before train program
-        # quite hackish, OTOH, it is generally uncommon that the eval
-        # program will be run before the train program
-        if self.mode == 'train' and 'eval' in self._compiled_progs:
-            del self._compiled_progs['eval']
-
         compiled_prog = fluid.CompiledProgram(prog)
-        loss_name = None
-        if self._loss_endpoint is not None:
-            loss_name = self._loss_endpoint.name
-        compiled_prog = compiled_prog.with_data_parallel(
-            loss_name=loss_name, places=places,
-            share_vars_from=share_vars_from)
+        if len(device_ids) > 1:
+            loss_name = None
+            if self.mode == 'train' and self._loss_endpoint is not None:
+                loss_name = self._loss_endpoint.name
+
+            share_vars_from = None
+            if self.mode == 'eval' and 'train' in self._compiled_progs:
+                share_vars_from = self._compiled_progs['train']
+            # HACK invalidate eval program if is compiled before train program
+            # quite hackish, OTOH, it is generally uncommon that the eval
+            # program will be run before the train program
+            if self.mode == 'train' and 'eval' in self._compiled_progs:
+                del self._compiled_progs['eval']
+
+            compiled_prog = compiled_prog.with_data_parallel(
+                loss_name=loss_name, places=places,
+                share_vars_from=share_vars_from)
+
         self._compiled_progs[self.mode] = compiled_prog
         return compiled_prog