DataLoader support not auto collate batch (#28425)

* DataLoader support not auto collate batch. test=develop

python/paddle/fluid/dataloader/dataloader_iter.py

@@ -36,6 +36,7 @@
 from ..framework import in_dygraph_mode
 from ..multiprocess_utils import CleanupFuncRegistrar, _cleanup_mmap, _set_SIGCHLD_handler
 from .fetcher import _IterableDatasetFetcher, _MapDatasetFetcher
+from .batch_sampler import _InfiniteIterableSampler
 
 __all__ = ['get_worker_info']
 
@@ -100,11 +101,13 @@ class _DatasetKind(object):
     ITER = 1
 
     @staticmethod
-    def create_fetcher(kind, dataset, collate_fn, drop_last):
+    def create_fetcher(kind, dataset, auto_collate_batch, collate_fn, drop_last):
         if kind == _DatasetKind.MAP:
-            return _MapDatasetFetcher(dataset, collate_fn, drop_last)
+            return _MapDatasetFetcher(dataset, auto_collate_batch,
+                                      collate_fn, drop_last)
         elif kind == _DatasetKind.ITER:
-            return _IterableDatasetFetcher(dataset, collate_fn, drop_last)
+            return _IterableDatasetFetcher(dataset, auto_collate_batch,
+                                           collate_fn, drop_last)
         else:
             raise NotImplementedError("unknown Dataset kind {}".format(kind))
 
@@ -221,8 +224,7 @@ def __init__(self, loader):
         self._places = loader.places
         self._return_list = loader.return_list
         self._batch_sampler = loader.batch_sampler
-        self._sampler_iter = iter(loader.batch_sampler)
-        self._collate_fn = loader.collate_fn or default_collate_fn
+        self._auto_collate_batch = loader.auto_collate_batch
         self._num_workers = loader.num_workers
         self._use_buffer_reader = loader.use_buffer_reader
         self._use_shared_memory = loader.use_shared_memory
@@ -231,6 +233,16 @@ def __init__(self, loader):
         self._dataset_kind = loader.dataset_kind
         self._pin_memory = loader.pin_memory
 
+        if self._auto_collate_batch:
+            self._sampler_iter = iter(loader.batch_sampler)
+            self._collate_fn = loader.collate_fn or default_collate_fn
+        else:
+            if self._dataset_kind == _DatasetKind.MAP:
+                self._sampler_iter = iter(list(range(len(self._dataset))))
+            else:
+                self._sampler_iter = iter(_InfiniteIterableSampler(self._dataset, 1))
+            self._collate_fn = loader.collate_fn
+
         # LoDTensorBlockingQueue instance for create_py_reader and a thread
         # to put mini-batch data to self._blocking_queue, mini-batch data
         # will be get from:
@@ -257,7 +269,8 @@ def __init__(self, loader):
         super(_DataLoaderIterSingleProcess, self).__init__(loader)
 
         self._dataset_fetcher = _DatasetKind.create_fetcher(
-            self._dataset_kind, self._dataset, self._collate_fn, True)
+            self._dataset_kind, self._dataset, self._auto_collate_batch,
+            self._collate_fn, True)
 
         # NOTE: len(self._places) batch data compose as an output
         # iteration, set blocking_queue can cache 2 iteration datas
@@ -367,7 +380,7 @@ def __del__(self):
 
 # NOTE(chenweihang): _worker_loop must be top level method to be pickled
 def _worker_loop(dataset, dataset_kind, indices_queue, out_queue, done_event,
-                 collate_fn, init_fn, worker_id, num_workers,
+                 auto_collate_batch, collate_fn, init_fn, worker_id, num_workers,
                  use_shared_memory):
     try:
         # NOTE: [ mmap files clear ] When the child process exits unexpectedly,
@@ -388,7 +401,7 @@ def _worker_loop(dataset, dataset_kind, indices_queue, out_queue, done_event,
             if init_fn is not None:
                 init_fn(worker_id)
             fetcher = _DatasetKind.create_fetcher(dataset_kind, dataset,
-                                                  collate_fn, True)
+                                    auto_collate_batch, collate_fn, True)
         except:
             init_exception = Exception("init_fn failed in worker {}: " \
                                     "{}".format(worker_id, sys.exc_info()))
@@ -511,8 +524,9 @@ def _init_workers(self):
                 target=_worker_loop,
                 args=(self._dataset, self._dataset_kind, indices_queue,
                       self._data_queue, self._workers_done_event,
-                      self._collate_fn, self._worker_init_fn, i,
-                      self._num_workers, self._use_shared_memory))
+                      self._auto_collate_batch, self._collate_fn,
+                      self._worker_init_fn, i, self._num_workers,
+                      self._use_shared_memory))
             worker.daemon = True
             worker.start()
             self._workers.append(worker)

python/paddle/fluid/dataloader/fetcher.py

@@ -14,8 +14,9 @@
 
 
 class _DatasetFetcher(object):
-    def __init__(self, dataset, collate_fn, drop_last):
+    def __init__(self, dataset, auto_collate_batch, collate_fn, drop_last):
         self.dataset = dataset
+        self.auto_collate_batch = auto_collate_batch
         self.collate_fn = collate_fn
         self.drop_last = drop_last
 
@@ -25,29 +26,41 @@ def fetch(self, batch_indices):
 
 
 class _IterableDatasetFetcher(_DatasetFetcher):
-    def __init__(self, dataset, collate_fn, drop_last):
-        super(_IterableDatasetFetcher, self).__init__(dataset, collate_fn,
-                                                      drop_last)
+    def __init__(self, dataset, auto_collate_batch, collate_fn, drop_last):
+        super(_IterableDatasetFetcher, self).__init__(dataset, auto_collate_batch,
+                                              collate_fn, drop_last)
         self.dataset_iter = iter(dataset)
 
     def fetch(self, batch_indices):
-        data = []
-        for _ in batch_indices:
-            try:
-                data.append(next(self.dataset_iter))
-            except StopIteration:
-                break
-        if len(data) == 0 or (self.drop_last and
-                              len(data) < len(batch_indices)):
-            raise StopIteration
 
-        return self.collate_fn(data)
+        if self.auto_collate_batch:
+            data = []
+            for _ in batch_indices:
+                try:
+                    data.append(next(self.dataset_iter))
+                except StopIteration:
+                    break
+            if len(data) == 0 or (self.drop_last and
+                                  len(data) < len(batch_indices)):
+                raise StopIteration
+        else:
+            data = next(self.dataset_iter)
+
+        if self.collate_fn:
+            data = self.collate_fn(data)
+        return data
 
 
 class _MapDatasetFetcher(_DatasetFetcher):
-    def __init__(self, dataset, collate_fn, drop_last):
-        super(_MapDatasetFetcher, self).__init__(dataset, collate_fn, drop_last)
+    def __init__(self, dataset, auto_collate_batch, collate_fn, drop_last):
+        super(_MapDatasetFetcher, self).__init__(dataset, auto_collate_batch, collate_fn, drop_last)
 
     def fetch(self, batch_indices):
-        data = [self.dataset[idx] for idx in batch_indices]
-        return self.collate_fn(data)
+        if self.auto_collate_batch:
+            data = [self.dataset[idx] for idx in batch_indices]
+        else:
+            data = self.dataset[batch_indices]
+
+        if self.collate_fn:
+            data = self.collate_fn(data)
+        return data

python/paddle/fluid/reader.py

@@ -163,6 +163,21 @@ class DataLoader(object):
 
     For :code:`batch_sampler` please see :code:`paddle.io.BatchSampler`
 
+    **Disable automatic batching**
+
+    In certain cases such as some NLP tasks, instead of automatic batching,
+    handling batching manually in dataset is needed by users. For these
+    cases, automatic batching is disabled if both :attr:`batch_size` and
+    :attr:`batch_sampler` is set as None, each data got from :attr:`dataset`
+    should be batched data and will be processed with function define by
+    :attr:`collate_fn` or :attr:`default_collate_fn`.
+
+
+    .. note::
+        When automatic batching is disabled, :attr:`default_collate_fn` will
+        do nothing to data from dataset.
+
+
     Args:  
         dataset(Dataset): the dataset to load data from, should be an
             instance of subclass of :code:`paddle.io.Dataset` or
@@ -185,7 +200,7 @@ class DataLoader(object):
         batch_sampler(BatchSampler): an instance of `paddle.io.BatchSampler`
             to generate batch indices to draw samples from :attr:`dataset`
             and combine a batch. Default None.
-        batch_size(int): sample number in a mini-batch, a substitution
+        batch_size(int|None): sample number in a mini-batch, a substitution
             parameter for :attr:`batch_sampler`, if :attr:`batch_sampler`
             is not set, a default `paddle.io.BatchSampler` will be used
             and initialize by :attr:`batch_size`, :attr:`shuffle` and
@@ -358,10 +373,15 @@ def __init__(self,
                 "batch_size/shuffle/drop_last should not be set when " \
                 "batch_sampler is given"
             self.batch_sampler = batch_sampler
+            self.batch_size = None
+        elif batch_size is None:
+            self.batch_sampler = None
+            self.batch_size = None
         else:
-            assert batch_size is not None and batch_size > 0, \
-                "batch_size should be a positive value when " \
+            assert batch_size > 0, \
+                "batch_size should be None or a positive value when " \
                 "batch_sampler is not given"
+            self.batch_size = batch_size
             if isinstance(dataset, IterableDataset):
                 self.batch_sampler = _InfiniteIterableSampler(dataset,
                                                               batch_size)
@@ -372,13 +392,21 @@ def __init__(self,
                     shuffle=shuffle,
                     drop_last=drop_last)
 
+        self.auto_collate_batch = self.batch_sampler is not None
+
         self.pin_memory = False
         if in_dygraph_mode():
             self.pin_memory = True if use_pinned_memory(
             ) is None else use_pinned_memory()
 
     def __len__(self):
-        return len(self.batch_sampler)
+        if self.dataset_kind == _DatasetKind.ITER:
+            raise ValueError("length of IterableDataset not supported")
+        else:
+            if self.batch_size is None:
+                return len(self.dataset)
+            else:
+                return len(self.batch_sampler)
 
     def __iter__(self):
         if self.num_workers == 0:

python/paddle/fluid/tests/unittests/test_multiprocess_dataloader_dynamic.py

@@ -27,7 +27,7 @@
 from paddle.fluid.dygraph.nn import Linear
 from paddle.fluid.dygraph.base import to_variable
 
-from test_multiprocess_dataloader_static import RandomDataset, prepare_places
+from test_multiprocess_dataloader_static import RandomDataset, RandomBatchedDataset, prepare_places
 from test_multiprocess_dataloader_static import EPOCH_NUM, BATCH_SIZE, IMAGE_SIZE, SAMPLE_NUM, CLASS_NUM
 
 
@@ -122,5 +122,48 @@ def test_main(self):
             self.assertLess(diff, 1e-2)
 
 
+class TestDygraphDataLoaderWithBatchedDataset(TestDygraphDataLoader):
+    def run_main(self, num_workers, places):
+        fluid.default_startup_program().random_seed = 1
+        fluid.default_main_program().random_seed = 1
+        with fluid.dygraph.guard(places[0]):
+            fc_net = SimpleFCNet()
+            optimizer = fluid.optimizer.Adam(parameter_list=fc_net.parameters())
+
+            dataset = RandomBatchedDataset(SAMPLE_NUM, CLASS_NUM)
+            dataloader = DataLoader(
+                dataset,
+                num_workers=num_workers,
+                batch_size=None,
+                drop_last=True)
+            assert len(dataloader) == int(SAMPLE_NUM / BATCH_SIZE)
+
+            step_list = []
+            loss_list = []
+            start_t = time.time()
+            for _ in six.moves.range(EPOCH_NUM):
+                step = 0
+                for image, label in dataloader():
+                    out = fc_net(image)
+                    loss = fluid.layers.cross_entropy(out, label)
+                    avg_loss = fluid.layers.reduce_mean(loss)
+                    avg_loss.backward()
+                    optimizer.minimize(avg_loss)
+                    fc_net.clear_gradients()
+
+                    loss_list.append(np.mean(avg_loss.numpy()))
+                    step += 1
+                step_list.append(step)
+
+        end_t = time.time()
+        ret = {
+            "time": end_t - start_t,
+            "step": step_list,
+            "loss": np.array(loss_list)
+        }
+        print("time cost", ret['time'], 'step_list', ret['step'])
+        return ret
+
+
 if __name__ == '__main__':
     unittest.main()

python/paddle/fluid/tests/unittests/test_multiprocess_dataloader_exception.py

@@ -188,7 +188,7 @@ def _collate_fn(sample_list):
                 indices_queue.put(None)
                 _worker_loop(loader._dataset, 0, indices_queue,
                              loader._data_queue, loader._workers_done_event,
-                             _collate_fn, _init_fn, 0, 1,
+                             True, _collate_fn, _init_fn, 0, 1,
                              loader._use_shared_memory)
                 self.assertTrue(False)
         except AssertionError:
@@ -232,7 +232,7 @@ def _collate_fn(sample_list):
                 loader._workers_done_event.set()
                 _worker_loop(loader._dataset, 0, indices_queue,
                              loader._data_queue, loader._workers_done_event,
-                             _collate_fn, _init_fn, 0, 1,
+                             True, _collate_fn, _init_fn, 0, 1,
                              loader._use_shared_memory)
                 self.assertTrue(True)
         except AssertionError:

python/paddle/fluid/tests/unittests/test_multiprocess_dataloader_iterable_dataset_dynamic.py

@@ -27,7 +27,7 @@
 from paddle.fluid.dygraph.nn import Linear
 from paddle.fluid.dygraph.base import to_variable
 
-from test_multiprocess_dataloader_iterable_dataset_static import RandomDataset, prepare_places
+from test_multiprocess_dataloader_iterable_dataset_static import RandomDataset, RandomBatchedDataset, prepare_places
 from test_multiprocess_dataloader_iterable_dataset_static import EPOCH_NUM, BATCH_SIZE, IMAGE_SIZE, SAMPLE_NUM, CLASS_NUM
 
 
@@ -119,5 +119,46 @@ def test_main(self):
                 0]
 
 
+class TestDygraphDataLoaderWithBatchedDataset(TestDygraphDataLoader):
+    def run_main(self, num_workers, places):
+        fluid.default_startup_program().random_seed = 1
+        fluid.default_main_program().random_seed = 1
+        with fluid.dygraph.guard(places[0]):
+            fc_net = SimpleFCNet()
+            optimizer = fluid.optimizer.Adam(parameter_list=fc_net.parameters())
+
+            dataset = RandomBatchedDataset(SAMPLE_NUM, CLASS_NUM)
+            dataloader = DataLoader(
+                dataset,
+                num_workers=num_workers,
+                batch_size=None,
+                drop_last=True)
+
+            step_list = []
+            loss_list = []
+            start_t = time.time()
+            for _ in six.moves.range(EPOCH_NUM):
+                step = 0
+                for image, label in dataloader():
+                    out = fc_net(image)
+                    loss = fluid.layers.cross_entropy(out, label)
+                    avg_loss = fluid.layers.reduce_mean(loss)
+                    avg_loss.backward()
+                    optimizer.minimize(avg_loss)
+                    fc_net.clear_gradients()
+
+                    loss_list.append(np.mean(avg_loss.numpy()))
+                    step += 1
+                step_list.append(step)
+
+        end_t = time.time()
+        ret = {
+            "time": end_t - start_t,
+            "step": step_list,
+            "loss": np.array(loss_list)
+        }
+        print("time cost", ret['time'], 'step_list', ret['step'])
+        return ret
+
 if __name__ == '__main__':
     unittest.main()