Bugfix parallel desc shared ptr (#996)

* fix bug

* reduce one copy

oneflow/core/graph/logical_graph.cpp

@@ -45,24 +45,27 @@ void LogicalGraph::NaiveBuildFwStruct(
     HashMap<std::string, std::vector<LogicalNode*>>* op_name2nodes) {
   const DLNetConf& dlnet_conf = Global<JobDesc>::Get()->dlnet_conf();
   const Placement& placement = Global<JobDesc>::Get()->placement();
-  HashMap<std::string, ParallelDesc*> name2parallel_desc;
+  HashMap<std::string, std::shared_ptr<ParallelDesc>> name2parallel_desc;
   for (const PlacementGroup& p_group : placement.placement_group()) {
     for (const std::string& op_name : p_group.op_set().op_name()) {
-      auto parallel_desc_raw_ptr = new ParallelDesc(p_group.parallel_conf());
-      CHECK(name2parallel_desc.emplace(op_name, parallel_desc_raw_ptr).second);
+      CHECK(name2parallel_desc
+                .emplace(op_name, std::make_shared<ParallelDesc>(p_group.parallel_conf()))
+                .second);
     }
   }
 
   HashMap<LogicalBlobId, LogicalNode*> lbi2producer;
   for (OperatorConf cur_op_conf : dlnet_conf.op()) {
-    ParallelDesc* parallel_desc_raw_ptr = name2parallel_desc.at(cur_op_conf.name());
-    cur_op_conf.set_device_type(parallel_desc_raw_ptr->device_type());
+    auto parallel_desc_ptr_it = name2parallel_desc.find(cur_op_conf.name());
+    CHECK(parallel_desc_ptr_it != name2parallel_desc.end());
+    const std::shared_ptr<ParallelDesc>& parallel_desc_ptr = parallel_desc_ptr_it->second;
+    cur_op_conf.set_device_type(parallel_desc_ptr->device_type());
     std::shared_ptr<Operator> cur_op = ConstructOp(cur_op_conf);
     LogicalNode* cur_node = cur_op->NewProperLogicalNode();
     AddAllocatedNode(cur_node);
     cur_node->mut_op_vec() = {cur_op};
-    cur_node->SoleOp()->FixParallelDesc(parallel_desc_raw_ptr);
-    cur_node->mut_parallel_desc().reset(parallel_desc_raw_ptr);
+    cur_node->SoleOp()->FixParallelDesc(parallel_desc_ptr.get());
+    cur_node->mut_parallel_desc() = parallel_desc_ptr;
     for (const std::string& obn : cur_node->SoleOp()->output_bns()) {
       const LogicalBlobId& lbi = cur_node->SoleOp()->BnInOp2Lbi(obn);
       CHECK(lbi2producer.emplace(lbi, cur_node).second);