fix unit tests

paddle/fluid/operators/listen_and_serv_op.cc

@@ -262,7 +262,7 @@ void ListenAndServOp::RunImpl(const framework::Scope &scope,
 
   auto optimize_blocks =
       Attr<std::vector<framework::BlockDesc *>>(kOptimizeBlocks);
-  PADDLE_ENFORCE(optimize_blocks.size() > 1,
+  PADDLE_ENFORCE(optimize_blocks.size() >= 1,
                  "optimize blocks should be 1 at least on the pserver side.");
   auto *program = optimize_blocks[0]->Program();
   framework::Executor executor(dev_place);

python/paddle/fluid/framework.py

@@ -558,19 +558,20 @@ class Operator(object):
                 if (attr_name not in self.attrs) or (
                         self.attrs[attr_name] is None):
                     continue
-                if isinstance(self.attrs[attr_name], Block):
+                attr_val = self.attrs[attr_name]
+                if isinstance(attr_val, Block):
                     self.desc.set_block_attr(attr_name,
                                              self.attrs[attr_name].desc)
-                elif isinstance(self.attrs[attr_name], list) and \
-                      all(isinstance(v, Block) for v in self.attrs[attr_name]):
-                    self.desc.set_blocks_attr(
-                        attr_name, [v.desc for v in self.attrs[attr_name]])
-                elif isinstance(self.attrs[attr_name], core.BlockDesc) or \
-                        isinstance(self.attrs[attr_name], core.ProgramDesc):
+                elif isinstance(attr_val, list) and attr_val and \
+                      all(isinstance(v, Block) for v in attr_val):
+                    self.desc.set_blocks_attr(attr_name,
+                                              [v.desc for v in attr_val])
+                elif isinstance(attr_val, core.BlockDesc) or \
+                        isinstance(attr_val, core.ProgramDesc):
                     self.desc.set_serialized_attr(
-                        attr_name, self.attrs[attr_name].serialize_to_string())
+                        attr_name, attr_val.serialize_to_string())
                 else:
-                    self.desc.set_attr(attr_name, self.attrs[attr_name])
+                    self.desc.set_attr(attr_name, attr_val)
         self.desc.check_attrs()
         if self.has_kernel(type):
             self.desc.infer_var_type(self.block.desc)
@@ -719,7 +720,8 @@ class Operator(object):
         self.attrs[name] = val
         if isinstance(val, Block):
             self.desc.set_block_attr(name, val.desc)
-        elif isinstance(val, list) and all(isinstance(v, Block) for v in val):
+        elif isinstance(val, list) and val and all(
+                isinstance(v, Block) for v in val):
             self.desc.set_blocks_attr(name, [v.desc for v in val])
         elif isinstance(val, core.BlockDesc) or \
                 isinstance(val, core.ProgramDesc):

python/paddle/fluid/layers/io.py

@@ -186,7 +186,6 @@ class ListenAndServ(object):
         main_program = self.helper.main_program
         current_block = main_program.current_block()
         parent_block = self.parent_block()
-        empty_block = Program().global_block()
 
         parent_block.append_op(
             type='listen_and_serv',
@@ -195,8 +194,9 @@ class ListenAndServ(object):
             attrs={
                 'endpoint': self.endpoint,
                 'Fanin': self.fan_in,
-                'OptimizeBlock': current_block,
-                'PrefetchBlock': empty_block,
+                'optimize_blocks': [
+                    current_block
+                ],  # did not support multiple optimize blocks in layers
                 'sync_mode': True,  # did not support async now in layers
                 'grad_to_block_id': [""]
             })