code optimize

paddle/fluid/framework/details/async_ssa_graph_executor.cc

@@ -68,12 +68,6 @@ FeedFetchList AsyncSSAGraphExecutor::Run(
 
     if (pool_) {
       run_futures.emplace_back(pool_->enqueue(std::move(call)));
-    } else {
-      fetch_data.emplace_back(std::move(call()));
-    }
-  }
-
-  if (pool_) {
       for (auto &f : run_futures) {
         if (exception_holder_.IsCaught()) {
           f.wait();
@@ -81,7 +75,11 @@ FeedFetchList AsyncSSAGraphExecutor::Run(
           fetch_data.emplace_back(std::move(f.get()));
         }
       }
+    } else {
+      fetch_data.emplace_back(std::move(call()));
     }
+  }
+
   if (exception_holder_.IsCaught()) {
     exception_holder_.ReThrow();
   }