Replace use of py::handle to store global_registry

Use py::gil_safe_call_once_and_store facility pybind11 provides.

Author: oleksandr-pavlyk

python/src/py_nvbench.cpp

@@ -124,7 +124,8 @@ struct nvbench_run_error : std::runtime_error
   // that are defined for the base class
   using std::runtime_error::runtime_error;
 };
-py::handle benchmark_exc{};
+
+PYBIND11_CONSTINIT static py::gil_safe_call_once_and_store<py::object> exc_storage;
 
 void run_interruptible(nvbench::option_parser &parser)
 {
@@ -223,18 +224,18 @@ class GlobalBenchmarkRegistry
     }
     catch (py::error_already_set &e)
     {
-      py::raise_from(e, benchmark_exc.ptr(), "Python error raised ");
+      py::raise_from(e, exc_storage.get_stored().ptr(), "Python error raised ");
       throw py::error_already_set();
     }
     catch (const std::exception &e)
     {
       const std::string &exc_message = e.what();
-      py::set_error(benchmark_exc, exc_message.c_str());
+      py::set_error(exc_storage.get_stored(), exc_message.c_str());
       throw py::error_already_set();
     }
     catch (...)
     {
-      py::set_error(benchmark_exc, "Caught unknown exception in nvbench_main");
+      py::set_error(exc_storage.get_stored(), "Caught unknown exception in nvbench_main");
       throw py::error_already_set();
     }
   }
@@ -1162,11 +1163,12 @@ PYBIND11_MODULE(PYBIND11_MODULE_NAME, m)
   static constexpr const char *exception_nvbench_runtime_error_doc = R"XXXX(
 An exception raised if running benchmarks encounters an error
 )XXXX";
-  py::object benchmark_exc_ =
-    py::exception<nvbench_run_error>(m, "NVBenchRuntimeError", PyExc_RuntimeError);
-  benchmark_exc_.attr("__doc__") = exception_nvbench_runtime_error_doc;
-
-  benchmark_exc = benchmark_exc_.release();
+  exc_storage.call_once_and_store_result([&]() {
+    py::object benchmark_exc_ =
+      py::exception<nvbench_run_error>(m, "NVBenchRuntimeError", PyExc_RuntimeError);
+    benchmark_exc_.attr("__doc__") = exception_nvbench_runtime_error_doc;
+    return benchmark_exc_;
+  });
 
   // ATTN: nvbench::benchmark_manager is a singleton, it is exposed through
   // GlobalBenchmarkRegistry class
@@ -1175,7 +1177,7 @@ An exception raised if running benchmarks encounters an error
                                                            py::nodelete{});
 
   // function register
-  auto func_register_impl = [&](py::object fn) { return std::ref(global_registry->add_bench(fn)); };
+  auto func_register_impl = [](py::object fn) { return std::ref(global_registry->add_bench(fn)); };
   static constexpr const char *func_register_doc = R"XXXX(
 Register benchmark function of type Callable[[nvbench.State], None]
 )XXXX";
@@ -1210,7 +1212,7 @@ Register benchmark function of type Callable[[nvbench.State], None]
   // Testing utilities
   m.def("test_cpp_exception", []() { throw nvbench_run_error("Test"); });
   m.def("test_py_exception", []() {
-    py::set_error(benchmark_exc, "Test");
+    py::set_error(exc_storage.get_stored(), "Test");
     throw py::error_already_set();
   });
 }