add doc string for async_executor.py

python/paddle/fluid/async_executor.py

@@ -89,8 +89,14 @@ class AsyncExecutor(object):
         self.executor = core.AsyncExecutor(scope, p)
         self.instance = None
 
-
-    def run(self, program, data_feed, filelist, thread_num, fetch, mode="", debug=False):
+    def run(self,
+            program,
+            data_feed,
+            filelist,
+            thread_num,
+            fetch,
+            mode="",
+            debug=False):
         """
         Run program by this AsyncExecutor. Training dataset will be in filelist.
         Users can also inspect certain variables by naming them in parameter
@@ -110,6 +116,7 @@ class AsyncExecutor(object):
             thread_num(int): number of concurrent training threads. See
                              :code:`Note` for how to set this properly
             fetch(str|list): the var name or a list of var names to inspect
+            mode(str): run mode of this interface
             debug(bool): When set to True, fetch vars will be printed to
                          standard output after each minibatch
 
@@ -154,14 +161,37 @@ class AsyncExecutor(object):
                                      data_feed.desc(), filelist, thread_num,
                                      fetch_var_names, mode, debug)
 
-    def download_data(self, afs_path, local_path, fs_default_name, ugi, file_cnt, hadoop_home="$HADOOP_HOME", process_num=12):
+    def download_data(self,
+                      afs_path,
+                      local_path,
+                      fs_default_name,
+                      ugi,
+                      file_cnt,
+                      hadoop_home="$HADOOP_HOME",
+                      process_num=12):
+        """
+        download_data is a default download method for distributed training
+        a user download data without this method
+        
+        Example:
+            >>> exe = fluid.AsyncExecutor()
+            >>> exe.download_data("/xxx/xxx/xx/",
+            >>>                   "./data", "afs://            
+            >>>  xxx.xxx.xxx.xxx:9901", "xxx,yyy")
+        Args:
+            afs_path(str): afs_path defined by users
+            local_path(str): download data path
+            fs_default_name(str): file system server address
+            ugi(str): hadoop ugi
+            file_cn(int): a user can specify file number for debugging
+            hadoop_home(str): hadoop home path
+            process_num(int): download process num
+        """
         if self.instance is None:
-            raise ValueError('instance is None, please run config_distributed_nodes init instance')
+            raise ValueError('instance is None, please run'
+                             'config_distributed_nodes init instance')
 
-        configs = {
-            "fs.default.name": fs_default_name,
-            "hadoop.job.ugi": ugi
-        }
+        configs = {"fs.default.name": fs_default_name, "hadoop.job.ugi": ugi}
 
         client = hdfs.HDFSClient(hadoop_home, configs)
         downloads = hdfs.multi_download(
@@ -172,35 +202,53 @@ class AsyncExecutor(object):
             self.instance.get_node_cnt() / 2,
             file_cnt,
             multi_processes=process_num)
-        #self.instance.barrier_all() #wait for download_data #TODO only barriere worker
-        self.instance.barrier_worker() #wait for download_data #TODO only barriere worker
-
-    def config_distributed_nodes(self):
-        self.instance = ps_instance.PaddlePSInstance(1, 2)
-        return self.instance
-
-        # get total rank
-        # get rank index
-        # get iplists
-        # get hadoop info
-        pass
+        self.instance.barrier_worker()  #wait for download_data
 
     def get_instance(self):
+        """
+        get current node's instance so that user can do operations
+        in distributed setting
+        """
         if self.instance is None:
-            raise ValueError('instance is None, please run config_distributed_nodes init instance')
+            raise ValueError(
+                'instance is None, please run config_distributed_nodes init instance'
+            )
+        return self.instance
+
+    def config_distributed_nodes(self):
+        """
+        if a user needs to run distributed async executor
+        he or she needs to do a global configuration so that 
+        information of current process can be obtained
+        """
+        self.instance = ps_instance.PaddlePSInstance(1, 2)
         return self.instance
 
     def stop(self):
+        """
+        at the end of process, users should call stop to servers
+        and barrier all workers
+        """
         if self.instance is None:
-            raise ValueError('instance is None, please run config_distributed_nodes init instance')
+            raise ValueError(
+                'instance is None, please run config_distributed_nodes init instance'
+            )
         self.instance.barrier_worker()  #worker do all things
         if self.instance.is_first_worker():
             self.executor.stop_server()
         self.instance.barrier_worker()  #sync
 
     def init_server(self, dist_desc):
+        """
+        initialize server of current node if current process is a server
+        Args:
+        dist_desc(str): a protobuf string that describes 
+                        how to init a worker and a server
+        """
         if self.instance is None:
-            raise ValueError('instance is None, please run config_distributed_nodes init instance')
+            raise ValueError(
+                'instance is None, please run config_distributed_nodes init instance'
+            )
         self.executor.init_server(dist_desc, self.instance._rankid)
         ip = self.executor.start_server()
         self.instance.set_ip(ip)
@@ -210,27 +258,51 @@ class AsyncExecutor(object):
         self.instance.barrier_all()  #wait all worker start
 
     def init_worker(self, dist_desc, startup_program):
+        """
+        initialize worker of current node if current process is a worker
+        Args:
+        dist_desc(str): a protobuf string that describes
+                        how to init a worker and a server
+        startup_program(fluid.Program): startup program of current process
+        """
         if self.instance is None:
-            raise ValueError('instance is None, please run config_distributed_nodes init instance')
+            raise ValueError(
+                'instance is None, please run config_distributed_nodes init instance'
+            )
         place = core.CPUPlace()
         executor = Executor(place)
         executor.run(startup_program)
 
         self.instance.barrier_all()  #wait all server start
         ips = self.instance.gather_ips()
-        self.executor.init_worker(dist_desc, ips, self.instance.get_node_cnt(), self.instance._rankid)
+        self.executor.init_worker(dist_desc, ips,
+                                  self.instance.get_node_cnt(),
+                                  self.instance._rankid)
         self.instance.barrier_all()  #wait all worker start
         if self.instance.is_first_worker():
             self.executor.init_model()
         self.instance.barrier_worker()  #wait init model
 
     def init_model(self):
+        """
+        init_model command that can be invoked from one of the worker
+        model parameters are initialized in servers
+        """
         if self.instance is None:
-            raise ValueError('instance is None, please run config_distributed_nodes init instance')
+            raise ValueError(
+                'instance is None, please run config_distributed_nodes init instance'
+            )
         self.executor.init_model()
 
     def save_model(self, save_path):
+        """
+        save_model command that can be invoked from one of the worker
+        model parameters are saved in servers and upload to save_path of file system
+        Args:
+        save_path(str): path to file system
+        """
         if self.instance is None:
-            raise ValueError('instance is None, please run config_distributed_nodes init instance')
+            raise ValueError(
+                'instance is None, please run config_distributed_nodes init instance'
+            )
         self.executor.save_model(save_path)
-