fix python gil problem

Author: FeixLiu

paddle/fluid/pybind/bind_fleet_executor.cc

@@ -33,7 +33,8 @@ void BindFleetExecutor(py::module* m) {
  py::class_<FleetExecutor>(*m, "FleetExecutor")
  .def(py::init<const std::string&>())
  .def("init", &FleetExecutor::Init)
- .def("run", &FleetExecutor::Run);
+ .def("run", &FleetExecutor::Run,
+ py::call_guard<py::gil_scoped_release>());
 
  py::class_<TaskNode>(*m, "TaskNode")
  .def(py::init<const framework::ProgramDesc&, int64_t, int64_t, int64_t>())