fix pylayer name crash (#47323)

paddle/fluid/eager/pylayer/py_layer_node.h

@@ -31,6 +31,7 @@ class GradNodePyLayer : public GradNodeBase {
                   size_t bwd_out_slot_num)
       : GradNodeBase(bwd_in_slot_num, bwd_out_slot_num) {
     ctx_ = ctx;
+    name_ = "GradNodePyLayer_" + std::string(Py_TYPE(ctx_)->tp_name);
     Py_INCREF(ctx_);
   }
 
@@ -52,9 +53,7 @@ class GradNodePyLayer : public GradNodeBase {
 
   void ClearTensorWrappers() override { VLOG(6) << "Do nothing here now"; }
 
-  std::string name() override {
-    return "GradNodePyLayer_" + std::string(Py_TYPE(ctx_)->tp_name);
-  }
+  std::string name() override { return name_; }
 
   void SaveForwardOutputsMeta(
       const std::vector<std::vector<paddle::experimental::Tensor*>>&
@@ -84,6 +83,7 @@ class GradNodePyLayer : public GradNodeBase {
 
  private:
   PyObject* ctx_{nullptr};
+  std::string name_{""};
   std::vector<std::vector<phi::DenseTensorMeta>> forward_outputs_meta_;
   std::vector<std::vector<paddle::platform::Place>> forward_outputs_place_;
 };