.. _api_guide_executor_en:################Executor################:code:`Executor` realizes a simple executor in which all operators will be executed in order. You can run :code:`Executor` in a Python script. There are two kinds of executors in PaddlePaddle Fluid. One is single-thread executor which is the default option for :code:`Executor` and the other is the parallel executor which is illustrated in :ref:`api_guide_parallel_executor_en` . The config of `Executor` and :ref:`api_guide_parallel_executor_en` is different, it may be a bit confusing for some users. To make the executor more facility, we introduce :ref:`api_guide_compiled_program_en` , :ref:`api_guide_compiled_program_en` is used to transform a program for various optimizations, and it can be run by :code:`Executor`.The logic of :code:`Executor` is very simple. It is suggested to thoroughly run the model with :code:`Executor` in debugging phase on one computer and then switch to mode of multiple devices or multiple computers to compute.:code:`Executor` receives a :code:`Place` at construction, which can either be :ref:`api_fluid_CPUPlace` or :ref:`api_fluid_CUDAPlace`... code-block:: python # First create the Executor. place = fluid.CUDAPlace(0) if use_cuda else fluid.CPUPlace() exe = fluid.Executor(place) # Run the startup program once and only once. exe.run(fluid.default_startup_program()) # Run the main program directly. loss, = exe.run(fluid.default_main_program(), feed=feed_dict, fetch_list=[loss.name])For simple example please refer to `basics_fit_a_line <../../beginners_guide/basics/fit_a_line/README.html>`_- Related API : - :ref:`api_fluid_Executor`
