Revise python save load api using new load/save op (#7995)

* initial commit

* add get_parameters method

* add get_parameters method

* small fix

* address comments

* address comments

* address comments

* fix

python/paddle/v2/fluid/framework.py

@@ -489,7 +489,8 @@ class Operator(object):
         no_kernel_op_set = {
             'feed', 'fetch', 'save', 'load', 'recurrent',
             'rnn_memory_helper_grad', 'conditional_block', 'while', 'send',
-            'recv', 'listen_and_serv', 'parallel_do'
+            'recv', 'listen_and_serv', 'parallel_do', 'save_combine',
+            'load_combine'
         }
         if type not in no_kernel_op_set:
             self.desc.infer_var_type(self.block.desc)

python/paddle/v2/fluid/io.py

@@ -46,6 +46,9 @@ def is_parameter(var):
 
 
 def is_persistable(var):
+    if var.desc.type() == core.VarDesc.VarType.FEED_MINIBATCH or \
+       var.desc.type() == core.VarDesc.VarType.FETCH_LIST:
+        return False
     return var.persistable
 
 
@@ -60,7 +63,12 @@ def _clone_var_in_block_(block, var):
         persistable=True)
 
 
-def save_vars(executor, dirname, main_program=None, vars=None, predicate=None):
+def save_vars(executor,
+              dirname,
+              main_program=None,
+              vars=None,
+              predicate=None,
+              save_file_name=None):
     """
     Save variables to directory by executor.
 
@@ -69,9 +77,12 @@ def save_vars(executor, dirname, main_program=None, vars=None, predicate=None):
     :param main_program: program. If vars is None, then filter all variables in this
     program which fit `predicate`. Default default_main_program.
     :param predicate: The Predicate describes a callable that returns a variable
-    as a bool. If it returns true, the variables will be saved.
-    :param vars: variables need to be saved. If specify vars, program & predicate
+    as a bool. If it returns true, the corresponding input variable will be saved.
+    :param vars: variables need to be saved. If vars is specified, program & predicate
     will be ignored
+    :param save_file_name: The name of a single file that all vars are saved to. 
+    If it is None, save variables to separate files.
+
     :return: None
     """
     if vars is None:
@@ -83,21 +94,39 @@ def save_vars(executor, dirname, main_program=None, vars=None, predicate=None):
         save_vars(
             executor,
             dirname=dirname,
-            vars=filter(predicate, main_program.list_vars()))
+            vars=filter(predicate, main_program.list_vars()),
+            save_file_name=save_file_name)
     else:
         save_program = Program()
         save_block = save_program.global_block()
+
+        save_var_map = {}
         for each_var in vars:
             new_var = _clone_var_in_block_(save_block, each_var)
+            if save_file_name is None:
+                save_block.append_op(
+                    type='save',
+                    inputs={'X': [new_var]},
+                    outputs={},
+                    attrs={'file_path': os.path.join(dirname, new_var.name)})
+            else:
+                save_var_map[new_var.name] = new_var
+
+        if save_file_name is not None:
+            save_var_list = []
+            for name in sorted(save_var_map.keys()):
+                save_var_list.append(save_var_map[name])
+
             save_block.append_op(
-                type='save',
-                inputs={'X': [new_var]},
+                type='save_combine',
+                inputs={'X': save_var_list},
                 outputs={},
-                attrs={'file_path': os.path.join(dirname, new_var.name)})
+                attrs={'file_path': os.path.join(dirname, save_file_name)})
+
         executor.run(save_program)
 
 
-def save_params(executor, dirname, main_program=None):
+def save_params(executor, dirname, main_program=None, save_file_name=None):
     """
     Save all parameters to directory with executor.
     """
@@ -106,10 +135,12 @@ def save_params(executor, dirname, main_program=None):
         dirname=dirname,
         main_program=main_program,
         vars=None,
-        predicate=is_parameter)
+        predicate=is_parameter,
+        save_file_name=save_file_name)
 
 
-def save_persistables(executor, dirname, main_program=None):
+def save_persistables(executor, dirname, main_program=None,
+                      save_file_name=None):
     """
     Save all persistables to directory with executor.
     """
@@ -118,21 +149,30 @@ def save_persistables(executor, dirname, main_program=None):
         dirname=dirname,
         main_program=main_program,
         vars=None,
-        predicate=is_persistable)
+        predicate=is_persistable,
+        save_file_name=save_file_name)
 
 
-def load_vars(executor, dirname, main_program=None, vars=None, predicate=None):
+def load_vars(executor,
+              dirname,
+              main_program=None,
+              vars=None,
+              predicate=None,
+              load_file_name=None):
     """
     Load variables from directory by executor.
 
-    :param executor: executor that save variable
+    :param executor: executor that load variable
     :param dirname: directory path
     :param main_program: program. If vars is None, then filter all variables in this
     program which fit `predicate`. Default default_main_program().
     :param predicate: The Predicate describes a callable that returns a variable
-    as a bool. If it returns true, the variables will be loaded.
-    :param vars: variables need to be loaded. If specify vars, program &
+    as a bool. If it returns true, the corresponding input variable will be loaded.
+    :param vars: variables need to be loaded. If vars is specified, program &
     predicate will be ignored
+    :param load_file_name: The name of the single file that all vars are loaded from.   
+    If it is None, load variables from separate files.
+
     :return: None
     """
     if vars is None:
@@ -144,23 +184,40 @@ def load_vars(executor, dirname, main_program=None, vars=None, predicate=None):
         load_vars(
             executor,
             dirname=dirname,
-            vars=filter(predicate, main_program.list_vars()))
+            vars=filter(predicate, main_program.list_vars()),
+            load_file_name=load_file_name)
     else:
         load_prog = Program()
         load_block = load_prog.global_block()
+
+        load_var_map = {}
         for each_var in vars:
             assert isinstance(each_var, Variable)
             new_var = _clone_var_in_block_(load_block, each_var)
+            if load_file_name is None:
+                load_block.append_op(
+                    type='load',
+                    inputs={},
+                    outputs={'Out': [new_var]},
+                    attrs={'file_path': os.path.join(dirname, new_var.name)})
+            else:
+                load_var_map[new_var.name] = new_var
+
+        if load_file_name is not None:
+            load_var_list = []
+            for name in sorted(load_var_map.keys()):
+                load_var_list.append(load_var_map[name])
+
             load_block.append_op(
-                type='load',
+                type='load_combine',
                 inputs={},
-                outputs={"Out": [new_var]},
-                attrs={'file_path': os.path.join(dirname, new_var.name)})
+                outputs={"Out": load_var_list},
+                attrs={'file_path': os.path.join(dirname, load_file_name)})
 
         executor.run(load_prog)
 
 
-def load_params(executor, dirname, main_program=None):
+def load_params(executor, dirname, main_program=None, load_file_name=None):
     """
     load all parameters from directory by executor.
     """
@@ -168,10 +225,12 @@ def load_params(executor, dirname, main_program=None):
         executor,
         dirname=dirname,
         main_program=main_program,
-        predicate=is_parameter)
+        predicate=is_parameter,
+        load_file_name=load_file_name)
 
 
-def load_persistables(executor, dirname, main_program=None):
+def load_persistables(executor, dirname, main_program=None,
+                      load_file_name=None):
     """
     load all persistables from directory by executor.
     """
@@ -179,7 +238,8 @@ def load_persistables(executor, dirname, main_program=None):
         executor,
         dirname=dirname,
         main_program=main_program,
-        predicate=is_persistable)
+        predicate=is_persistable,
+        load_file_name=load_file_name)
 
 
 def get_inference_program(target_vars, main_program=None):
@@ -238,7 +298,8 @@ def save_inference_model(dirname,
                          feeded_var_names,
                          target_vars,
                          executor,
-                         main_program=None):
+                         main_program=None,
+                         save_file_name=None):
     """
     Build a model especially for inference,
     and save it to directory by the executor.
@@ -249,6 +310,8 @@ def save_inference_model(dirname,
     :param executor: executor that save inference model
     :param main_program: original program, which will be pruned to build the inference model.
             Default default_main_program().
+    :param save_file_name: The name of a single file that all parameters are saved to. 
+    If it is None, save parameters to separate files.
 
     :return: None
     """
@@ -283,25 +346,7 @@ def save_inference_model(dirname,
     with open(model_file_name, "wb") as f:
         f.write(inference_program.desc.serialize_to_string())
 
-    save_params(executor, dirname, main_program)
-
-
-def load_persistables_if_exist(executor, dirname, main_program=None):
-    filenames = next(os.walk(dirname))[2]
-    filenames = set(filenames)
-
-    def _is_presistable_and_exist_(var):
-        if not is_persistable(var):
-            return False
-        else:
-            return var.name in filenames
-
-    load_vars(
-        executor,
-        dirname,
-        main_program=main_program,
-        vars=None,
-        predicate=_is_presistable_and_exist_)
+    save_persistables(executor, dirname, inference_program, save_file_name)
 
 
 def get_feed_targets_names(program):
@@ -322,13 +367,15 @@ def get_fetch_targets_names(program):
     return fetch_targets_names
 
 
-def load_inference_model(dirname, executor):
+def load_inference_model(dirname, executor, load_file_name=None):
     """
     Load inference model from a directory
 
     :param dirname: directory path
     :param executor: executor that load inference model
-
+    :param load_file_name: The name of the single file that all parameters are loaded from.   
+    If it is None, load parameters from separate files.
+    
     :return: [program, feed_target_names, fetch_targets]
              program: program especially for inference.
              feed_target_names: Names of variables that need to feed data
@@ -342,7 +389,7 @@ def load_inference_model(dirname, executor):
         program_desc_str = f.read()
 
     program = Program.parse_from_string(program_desc_str)
-    load_persistables_if_exist(executor, dirname, program)
+    load_persistables(executor, dirname, program, load_file_name)
 
     feed_target_names = get_feed_targets_names(program)
     fetch_target_names = get_fetch_targets_names(program)
@@ -359,6 +406,7 @@ def get_parameter_value(para, executor):
 
     :param executor: executor for retrieving the value
     :param para: the given parameter
+
     :return: the LoDTensor for the parameter
     """
     assert is_parameter(para)
@@ -377,6 +425,7 @@ def get_parameter_value_by_name(name, executor, program=None):
     :param name: the name of the parameter
     :param program: the program where the variable is found
             Default default_main_program().
+
     :return: the LoDTensor for the variable
     """
     if program is None: