Fix a minor bug for distributed_spliter.round_robin

Also fixed typo and comments.

python/paddle/fluid/distribute_transpiler.py

@@ -17,7 +17,7 @@ import framework
 from framework import Program, default_main_program, default_startup_program, Parameter, Variable
 import optimizer
 from layer_helper import LayerHelper
-from distributed_spliter import *
+import distributed_splitter as splitter
 import math
 from . import core
 import debuger
@@ -138,7 +138,7 @@ class DistributeTranspiler:
                   program=None,
                   pservers="127.0.0.1:6174",
                   trainers=1,
-                  split_method=round_robin):
+                  split_method=splitter.round_robin):
         """
             Transpile the program to distributed data-parallelism programs.
             The main_program will be transformed to use a remote parameter server

python/paddle/fluid/distributed_splitter.py

@@ -17,8 +17,10 @@ def hash_name(varlist, pserver_endpoints):
     """
     hash variable names to several endpoints.
 
-    :param varlist: a list of Variables
-    :return: a map of pserver endpoint -> varname
+    Args:
+        varlist(list): a list of Variables
+
+    Returns(dict): a map of pserver endpoint -> varname
     """
 
     def _hash_block(block_str, total):
@@ -34,9 +36,14 @@ def hash_name(varlist, pserver_endpoints):
 
 def round_robin(varlist, pserver_endpoints):
     """
-    distribute variables to several endpoints.
+    Distribute variables to several endpoints.
+    Args:
+        varlist(list): a list of variables
+        pserver_endpoints(list): a list of pserver endpoints
+
+    Returns(list[int]): the endpoint for each variable
     """
-    assert (len(varlist) > len(pserver_endpoints))
+    assert (len(varlist) >= len(pserver_endpoints))
 
     eplist = []
     pserver_idx = 0