fix pylayer mem leak, test=develop (#41559)

paddle/fluid/eager/pylayer/py_layer_node.cc

@@ -154,6 +154,12 @@ operator()(
     }
   }
 
+  Py_XDECREF(backward_fn);
+  Py_XDECREF(backward_args);
+  if (!PyTuple_Check(outputs)) {
+    Py_XDECREF(outputs_tuple);
+  }
+
   return grad_out;
 }
 }  // namespace egr

paddle/fluid/pybind/eager_py_layer.cc

@@ -231,6 +231,10 @@ PyObject* pylayer_method_apply(PyObject* cls, PyObject* args,
   auto outputs = PyObject_Call(forward_fn, forward_args, kwargs);
   egr::Controller::Instance().SetHasGrad(trace_backward);
   if (!outputs) {
+    Py_XDECREF(forward_args);
+    Py_XDECREF(kwargs_value_list);
+    Py_XDECREF(backward_function);
+    Py_XDECREF(forward_fn);
     return nullptr;
   }
 
@@ -367,6 +371,14 @@ PyObject* pylayer_method_apply(PyObject* cls, PyObject* args,
     VLOG(6) << "PyLayer construct backward node finish...";
   }
 
+  if (!PyTuple_Check(outputs)) {
+    Py_XDECREF(outputs_tuple);
+  }
+  Py_XDECREF(forward_args);
+  Py_XDECREF(kwargs_value_list);
+  Py_XDECREF(backward_function);
+  Py_XDECREF(forward_fn);
+
   return outputs;
   EAGER_CATCH_AND_THROW_RETURN_NULL
 }