Add releaseOutput interface for release the output memory of the middle layer.

paddle/gserver/gradientmachines/GradientMachine.h

@@ -233,6 +233,13 @@ public:
     (void)numProcessed;
   }
 
+  /**
+   * @brief   Release the middle layer's output memory.
+   *
+   * @note    This function is used for memory optimization in inference.
+   */
+  virtual void releaseOutput() {}
+
 protected:
   virtual void onLoadParameter() {}
 

paddle/gserver/gradientmachines/NeuralNetwork.cpp

@@ -187,6 +187,31 @@ void NeuralNetwork::init(const ModelConfig& config,
     CHECK(it != layerMap_.end());
     outputLayers_.push_back(it->second);
   }
+
+  for (const auto& layer : layers_) {
+    const auto name& = layer->getName();
+    bool isMiddleLayer = true;
+
+    // if data layer
+    for (const auto& dataLayer : dataLayers_) {
+      if (name == dataLayer->getName()) {
+        isMiddleLayer = false;
+        break;
+      }
+    }
+
+    // if output layer
+    for (const auto& dataLayer : outputLayers_) {
+      if (name == dataLayer->getName()) {
+        isMiddleLayer = false;
+        break;
+      }
+    }
+
+    if (isMiddleLayer) {
+      middleLayers_.push_back(layer);
+    }
+  }
 }
 
 void NeuralNetwork::connect(LayerPtr agentLayer,
@@ -327,6 +352,13 @@ void NeuralNetwork::onPassEnd() {
   }
 }
 
+void NeuralNetwork::releaseOutput() {
+  for (auto& layer : middleLayers_) {
+    Argument& arg = layer->getOutput();
+    arg.value.reset();
+  }
+}
+
 #ifndef PADDLE_MOBILE_INFERENCE
 
 class CombinedEvaluator : public Evaluator {

paddle/gserver/gradientmachines/NeuralNetwork.h

@@ -137,6 +137,13 @@ public:
   /// some finish work, like convert the weight format of MKLDNNLayers
   void finish();
 
+  /**
+   * @brief   Release the middle layer's output memory.
+   *
+   * @note    This function is used for memory optimization in inference.
+   */
+  void releaseOutput();
+
 protected:
   /**
    * The constructor of NeuralNetwork.
@@ -158,6 +165,7 @@ protected:
 
   std::vector<DataLayerPtr> dataLayers_;
   std::vector<LayerPtr> outputLayers_;
+  std::vector<LayerPtr> middleLayers_;
 
   static std::map<std::string, bool> dllInitMap;