message: Release the GIL during FileExists to ensure other Python threads in the process can make progress.
diff: @@ -37,8 +37,12 @@ namespace py = pybind11;
  PYBIND11_MODULE(_pywrap_file_io, m) {
  m.def("FileExists", [](const std::string& filename) {
  - tensorflow::MaybeRaiseRegisteredFromStatus(
  - tensorflow::Env::Default()->FileExists(filename));
  + tensorflow::Status status;
  + {
  + py::gil_scoped_release release;
  + status = tensorflow::Env::Default()->FileExists(filename);
  + }
  + tensorflow::MaybeRaiseRegisteredFromStatus(status);
  });
  m.def("DeleteFile", [](const std::string& filename) {
  tensorflow::MaybeRaiseRegisteredFromStatus(
  