Add api to clear intermediate tensors in AnalysisPredictor (#25069)

* add api to clear intemediate tensors in analysis predictor. test=develop

* add python api. test=develop

paddle/fluid/inference/api/analysis_predictor.cc

@@ -828,6 +828,25 @@ bool AnalysisPredictor::LoadParameters() {
   return true;
 }
 
+void AnalysisPredictor::ClearIntermediateTensor() {
+  PADDLE_ENFORCE_NOT_NULL(inference_program_.get(),
+                          platform::errors::PreconditionNotMet(
+                              "The inference program should be loaded first."));
+  const auto &global_block = inference_program_->MutableBlock(0);
+  for (auto *var : global_block->AllVars()) {
+    if (!IsPersistable(var)) {
+      const std::string name = var->Name();
+      auto *variable = executor_->scope()->FindVar(name);
+      if (variable != nullptr && variable->IsType<framework::LoDTensor>() &&
+          name != "feed" && name != "fetch") {
+        VLOG(3) << "Clear Intermediate Tensor: " << name;
+        auto *t = variable->GetMutable<framework::LoDTensor>();
+        t->clear();
+      }
+    }
+  }
+}
+
 #if PADDLE_WITH_TENSORRT
 bool AnalysisPredictor::SaveTrtCalibToDisk() {
   PADDLE_ENFORCE(config_.tensorrt_engine_enabled(),

paddle/fluid/inference/api/analysis_predictor.h

@@ -187,6 +187,12 @@ class AnalysisPredictor : public PaddlePredictor {
   ///
   void OptimizeInferenceProgram();
 
+  ///
+  /// \brief Clear the intermediate tensors of the predictor
+  ///
+  ///
+  void ClearIntermediateTensor();
+
   ///
   /// \brief Get the argument used by predictor
   ///

paddle/fluid/inference/api/paddle_api.h

@@ -313,6 +313,12 @@ class PD_INFER_DECL PaddlePredictor {
   /// \return Whether the run is successful
   virtual bool ZeroCopyRun() { return false; }
 
+  ///
+  /// \brief Clear the intermediate tensors of the predictor
+  ///
+  ///
+  virtual void ClearIntermediateTensor() {}
+
   /// \brief Clone an existing predictor
   /// When using clone, the same network will be created,
   /// and the parameters between them are shared.

paddle/fluid/inference/tests/api/trt_mobilenet_test.cc

@@ -43,6 +43,7 @@ TEST(AnalysisPredictor, use_gpu) {
   std::vector<PaddleTensor> outputs;
   for (auto& input : inputs_all) {
     ASSERT_TRUE(predictor->Run(input, &outputs));
+    predictor->ClearIntermediateTensor();
   }
 }
 

paddle/fluid/pybind/inference_api.cc

@@ -501,6 +501,8 @@ void BindAnalysisPredictor(py::module *m) {
       .def("get_output_names", &AnalysisPredictor::GetOutputNames)
       .def("get_input_tensor_shape", &AnalysisPredictor::GetInputTensorShape)
       .def("zero_copy_run", &AnalysisPredictor::ZeroCopyRun)
+      .def("clear_intermediate_tensor",
+           &AnalysisPredictor::ClearIntermediateTensor)
       .def("create_feed_fetch_var", &AnalysisPredictor::CreateFeedFetchVar)
       .def("prepare_feed_fetch", &AnalysisPredictor::PrepareFeedFetch)
       .def("prepare_argument", &AnalysisPredictor::PrepareArgument)