fix PE fetch bug (#18644)

test=develop

paddle/fluid/framework/details/fast_threaded_ssa_graph_executor.cc

@@ -16,6 +16,7 @@
 #include <queue>
 #include <string>
 #include <unordered_map>
+#include <unordered_set>
 #include <vector>
 #include "paddle/fluid/framework/details/fetch_op_handle.h"
 #include "paddle/fluid/framework/details/multi_devices_helper.h"
@@ -124,7 +125,9 @@ void FastThreadedSSAGraphExecutor::InsertFetchOps(
     std::unordered_map<OpHandleBase *, std::atomic<int>> *op_deps,
     std::vector<OpHandleBase *> *fetch_ops,
     std::vector<OpHandleBase *> *ready_fetch_ops) {
-  for (auto &fetch_var_name : fetch_tensors) {
+  std::unordered_set<std::string> fetch_tensor_set(fetch_tensors.begin(),
+                                                   fetch_tensors.end());
+  for (auto &fetch_var_name : fetch_tensor_set) {
     for (auto &var_map : graph_->Get<GraphVars>(kGraphVars)) {
       auto it = var_map.find(fetch_var_name);
       if (it != var_map.end()) {

paddle/fluid/framework/details/threaded_ssa_graph_executor.cc

@@ -13,7 +13,6 @@
 // limitations under the License.
 
 #include "paddle/fluid/framework/details/threaded_ssa_graph_executor.h"
-
 #include "paddle/fluid/framework/ir/graph_helper.h"
 #include "paddle/fluid/platform/profiler.h"
 
@@ -157,7 +156,9 @@ void ThreadedSSAGraphExecutor::InsertFetchOps(
     FeedFetchList *fetch_data) {
   std::unordered_map<std::string, std::vector<VarHandleBase *>> fetched_vars;
   std::unordered_set<VarHandleBase *> local_ready_vars;
-  for (auto &fetch_var_name : fetch_tensors) {
+  std::unordered_set<std::string> fetch_tensor_set(fetch_tensors.begin(),
+                                                   fetch_tensors.end());
+  for (auto &fetch_var_name : fetch_tensor_set) {
     for (auto &var_map : graph_->Get<details::GraphVars>(details::kGraphVars)) {
       auto it = var_map.find(fetch_var_name);
       if (it != var_map.end()) {