add ps_instance doc

python/paddle/fluid/distributed/ps_instance.py

@@ -14,7 +14,17 @@
 import helper as dist_helper
 import sys
 
+
 class PaddlePSInstance(object):
+    """
+        PaddlePSInstance class is used to generate A instance of server or worker 
+        Args:
+            server_worker_mode: is a value 0 or 1, default is 1
+            proc_per_node: process per node, default is 2 
+        Examples:
+            instance = PaddlePSInstance(1, 2)
+    """
+
     def __init__(self, server_worker_mode, proc_per_node):
         self.dh = dist_helper.MPIHelper()
         self._rankid = self.dh.get_rank()
@@ -31,7 +41,6 @@ class PaddlePSInstance(object):
         self._comm = None
         self._split_comm()
 
-
     def _set_nodetype(self):
         if self._server_worker_mode == 0:
             if self._rankid < self._server_num:
@@ -47,7 +56,7 @@ class PaddlePSInstance(object):
                 else:
                     self._node_type = 1
             else:
-                self._node_type = -1;
+                self._node_type = -1
         else:
             self._node_type = -1
 
@@ -62,45 +71,78 @@ class PaddlePSInstance(object):
         pass
 
     def get_worker_index(self):
+        """
+        Return worker index 
+        """
         if self._server_worker_mode == 0:
             return self._rankid == self.server_num
         else:
             return self._rankid / self._proc_per_node
 
     def get_server_index(self):
+        """
+        Return server index 
+        """
         if self._server_worker_mode == 0:
             return self.rank_id
         else:
             return self.rank_id / self._proc_per_node
 
     def is_worker(self):
+        """
+        Return instance is worker or not
+        """
         return self._node_type == 1
 
     def is_server(self):
+        """
+        Return instance is server or not
+        """
         return self._node_type == 0
 
     def is_first_worker(self):
+        """
+        Return instance is first worker or not
+        """
         return self.is_worker() and 0 == self.get_worker_index()
 
     def set_ip(self, ip):
+        """
+            set server ip
+        """
         self._ip = ip
 
     def gather_ips(self):
+        """
+        Return all servers and workers ip throught mpi allgather 
+        """
         self._ips = self.dh.comm.allgather(self._ip)
         return self._ips
 
     def get_node_cnt(self):
+        """
+        Return node cnt
+        """
         return self._nodes
 
     def barrier_all(self):
+        """
+        barrier workers and servers
+        """
         self.dh.comm.barrier()
 
     def barrier_worker(self):
+        """
+        barrier workers
+        """
         if self.is_worker():
             self._comm.barrier()
         pass
 
     def finalize(self):
+        """
+        MPI finalize
+        """
         self.dh.finalize()
         pass