fix memory leak of optimizer and executer

cpp-package/example/alexnet.cpp

@@ -319,6 +319,7 @@ int main(int argc, char const *argv[]) {
   }
   /*don't foget to release the executor*/
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return 0;
 }

cpp-package/example/charRNN.cpp

@@ -500,6 +500,9 @@ void train(const std::string file, int batch_size, int max_epoch, int start_epoc
     std::string filepath = prefix + "-" + std::to_string(epoch) + ".params";
     SaveCheckpoint(filepath, RNN, exe);
   }
+
+  delete exe;
+  delete opt;
 }
 
 /*The original example, rnn_cell_demo.py, uses default Xavier as initalizer, which relies on
@@ -577,6 +580,9 @@ void trainWithBuiltInRNNOp(const std::string file, int batch_size, int max_epoch
     std::string filepath = prefix + "-" + std::to_string(epoch) + ".params";
     SaveCheckpoint(filepath, RNN, exe);
   }
+
+  delete exe;
+  delete opt;
 }
 
 void predict(std::wstring* ptext, int sequence_length, const std::string param_file,
@@ -639,6 +645,8 @@ void predict(std::wstring* ptext, int sequence_length, const std::string param_f
     next = charIndices[n];
     ptext->push_back(next);
   }
+
+  delete exe;
 }
 
 void predictWithBuiltInRNNOp(std::wstring* ptext, int sequence_length, const std::string param_file,
@@ -693,6 +701,8 @@ void predictWithBuiltInRNNOp(std::wstring* ptext, int sequence_length, const std
     next = charIndices[n];
     ptext->push_back(next);
   }
+
+  delete exe;
 }
 
 int main(int argc, char** argv) {

cpp-package/example/googlenet.cpp

@@ -190,6 +190,7 @@ int main(int argc, char const *argv[]) {
   }
 
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return 0;
 }

cpp-package/example/inception_bn.cpp

@@ -232,6 +232,7 @@ int main(int argc, char const *argv[]) {
     LG << "Validation Accuracy: " << val_acc.Get();
   }
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return 0;
 }

cpp-package/example/lenet.cpp

@@ -173,6 +173,7 @@ class Lenet {
          << ", accuracy: " << ValAccuracy(batch_size * 10, lenet);
     }
     delete exe;
+    delete opt;
   }
 
  private:

cpp-package/example/lenet_with_mxdataiter.cpp

@@ -177,6 +177,7 @@ int main(int argc, char const *argv[]) {
   }
 
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return 0;
 }

cpp-package/example/mlp_cpu.cpp

@@ -139,6 +139,7 @@ int main(int argc, char** argv) {
   }
 
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return 0;
 }

cpp-package/example/mlp_csv.cpp

@@ -267,6 +267,7 @@ int main(int argc, char** argv) {
     }
 
     delete exec;
+    delete opt;
     MXNotifyShutdown();
     return 0;
 }

cpp-package/example/mlp_gpu.cpp

@@ -155,6 +155,7 @@ int main(int argc, char** argv) {
   }
 
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return 0;
 }

cpp-package/example/resnet.cpp

@@ -242,6 +242,7 @@ int main(int argc, char const *argv[]) {
     LG << "Validation Accuracy: " << val_acc.Get();
   }
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return 0;
 }

cpp-package/example/test_optimizer.cpp

@@ -30,6 +30,7 @@ int main(int argc, char** argv) {
   opt = OptimizerRegistry::Find("adam");
   int ret = (opt == 0) ? 1 : 0;
 
+  delete opt;
   MXNotifyShutdown();
   return ret;
 }

cpp-package/example/test_score.cpp

@@ -156,6 +156,7 @@ int main(int argc, char** argv) {
   }
 
   delete exec;
+  delete opt;
   MXNotifyShutdown();
   return score >= MIN_SCORE ? 0 : 1;
 }