[DOC] Fix comment code of API create_py_reader_by_data (#18193)

* [DOC] Fix comment code of API create_py_reader_by_data. test=develop, test=document_preview

* Fix code style of API comment. test=develop,test=document_preview

Fix code style of API comment. test=develop,test=document_preview

* update api spec of api create_py_reader_by_data

* remove default config code. test=develop

* remove useless code. test=develop

* update create_py_reader_by_data api. test=develop

paddle/fluid/API.spec

@@ -249,7 +249,7 @@ paddle.fluid.layers.batch (ArgSpec(args=['reader', 'batch_size'], varargs=None,
 paddle.fluid.layers.double_buffer (ArgSpec(args=['reader', 'place', 'name'], varargs=None, keywords=None, defaults=(None, None)), ('document', 'c13b8a8521bea5f8123b925ae2a5d5db'))
 paddle.fluid.layers.random_data_generator (ArgSpec(args=['low', 'high', 'shapes', 'lod_levels', 'for_parallel'], varargs=None, keywords=None, defaults=(True,)), ('document', '9b7f0f86ec24bbc97643cadcb6499cff'))
 paddle.fluid.layers.py_reader (ArgSpec(args=['capacity', 'shapes', 'dtypes', 'lod_levels', 'name', 'use_double_buffer'], varargs=None, keywords=None, defaults=(None, None, True)), ('document', 'd78a1c7344955c5caed8dc13adb7beb6'))
-paddle.fluid.layers.create_py_reader_by_data (ArgSpec(args=['capacity', 'feed_list', 'name', 'use_double_buffer'], varargs=None, keywords=None, defaults=(None, True)), ('document', 'b42332b894e1e0962c6a43f0151c2640'))
+paddle.fluid.layers.create_py_reader_by_data (ArgSpec(args=['capacity', 'feed_list', 'name', 'use_double_buffer'], varargs=None, keywords=None, defaults=(None, True)), ('document', '2edf37d57862b24a7a26aa19a3573f73'))
 paddle.fluid.layers.Preprocessor.__init__ (ArgSpec(args=['self', 'reader', 'name'], varargs=None, keywords=None, defaults=(None,)), ('document', '6adf97f83acf6453d4a6a4b1070f3754'))
 paddle.fluid.layers.Preprocessor.block (ArgSpec(args=['self'], varargs=None, keywords=None, defaults=None), ('document', '6adf97f83acf6453d4a6a4b1070f3754'))
 paddle.fluid.layers.Preprocessor.inputs (ArgSpec(args=['self'], varargs=None, keywords=None, defaults=None), ('document', '6adf97f83acf6453d4a6a4b1070f3754'))

python/paddle/fluid/layers/io.py

@@ -828,6 +828,7 @@ def create_py_reader_by_data(capacity,
          import paddle
          import paddle.fluid as fluid
          import paddle.dataset.mnist as mnist
+         import paddle.fluid.compiler as compiler
 
          def network(img, label):
              # User defined network. Here a simple regression as example
@@ -835,6 +836,9 @@ def create_py_reader_by_data(capacity,
              loss = fluid.layers.cross_entropy(input=predict, label=label)
              return fluid.layers.mean(loss)
 
+         MEMORY_OPT = False
+         USE_CUDA = False
+
          image = fluid.layers.data(name='image', shape=[1, 28, 28], dtype='float32')
          label = fluid.layers.data(name='label', shape=[1], dtype='int64')
          reader = fluid.layers.create_py_reader_by_data(capacity=64,
@@ -846,14 +850,23 @@ def create_py_reader_by_data(capacity,
          img, label = fluid.layers.read_file(reader)
          loss = network(img, label)  # some network definition
 
-         fluid.Executor(fluid.CUDAPlace(0)).run(fluid.default_startup_program())
+         place = fluid.CUDAPlace(0) if USE_CUDA else fluid.CPUPlace()
+         exe = fluid.Executor(place)
+         exe.run(fluid.default_startup_program())
 
-         exe = fluid.ParallelExecutor(use_cuda=True, loss_name=loss.name)
-         for epoch_id in range(10):
+         build_strategy = fluid.BuildStrategy()
+         build_strategy.memory_optimize = True if MEMORY_OPT else False
+         compiled_prog = compiler.CompiledProgram(
+             fluid.default_main_program()).with_data_parallel(
+                 loss_name=loss.name,
+                 build_strategy=build_strategy,
+                 exec_strategy=exec_strategy)
+
+         for epoch_id in range(2):
              reader.start()
              try:
                  while True:
-                     exe.run(fetch_list=[loss.name])
+                     exe.run(compiled_prog, fetch_list=[loss.name])
              except fluid.core.EOFException:
                  reader.reset()
     """