fix training validation test=release/1.4 (#16716)

Author: baojun-nervana

paddle/fluid/operators/ngraph/ngraph_engine.cc

@@ -75,6 +75,7 @@ std::vector<std::string> NgraphEngine::feed_vars = {};
 std::vector<std::string> NgraphEngine::fetch_vars = {};
 framework::Variable* NgraphEngine::pre_var_ptr = nullptr;
 const framework::BlockDesc* NgraphEngine::p_bdesc = nullptr;
+bool NgraphEngine::is_training = false;
 
 std::unordered_map<std::string, EngineCache> NgraphEngine::engine_cache = {};
 std::unordered_map<std::string,
@@ -93,11 +94,13 @@ static std::vector<std::vector<int>> NgraphOpIntervals(
   int size = ops->size();
   int left = 0;
   while (left < size && ops->at(left)->Type() != framework::kFeedOpType &&
+         ops->at(left)->Type() != "read" &&
          ops->at(left)->Type() != framework::kFetchOpType) {
     ++left;
   }
 
-  while (left < size && ops->at(left)->Type() == framework::kFeedOpType) {
+  while (left < size && (ops->at(left)->Type() == framework::kFeedOpType ||
+                         ops->at(left)->Type() == "read")) {
     for (auto& var_name_item : ops->at(left)->Outputs()) {
       for (auto& var_name : var_name_item.second) {
         NgraphEngine::feed_vars.emplace_back(var_name);
@@ -270,6 +273,7 @@ void NgraphEngine::Prepare(const std::vector<int>& interval) {
 
   for (auto op_desc : ops_desc) {
     if (op_desc->Type().find("_grad") != std::string::npos) {
+      is_training = true;
       this->is_test_ = false;
       break;
     }
@@ -590,7 +594,7 @@ void NgraphEngine::Run(const framework::Scope& scope,
       }
       bool is_persistable =
           (p_persistables->find(vi) != p_persistables->end()) ? true : false;
-      if (is_test && is_persistable) {
+      if (!is_training && is_test && is_persistable) {
         ti->set_stale(false);
       }
       (*p_t_in).emplace_back(ti);

paddle/fluid/operators/ngraph/ngraph_engine.h

@@ -57,6 +57,7 @@ class NgraphEngine {
 
   void Run(const framework::Scope& scope, const platform::Place& place) const;
 
+  static bool is_training;
   static const framework::BlockDesc* p_bdesc;
   static std::vector<std::string> feed_vars, fetch_vars;