【MindSpore易点通】网络构建总结上篇

低阶API改下沉时dataset输出应和network输入匹配

低阶API模式训练，即使用for循环进行训练与验证。由于低阶API不支持数据下沉训练，因此需将低阶API改成高阶API，即可使用数据下沉模式进行训练，以提升性能。(本例中，性能对比：低阶API模式:770imgs/sec ；低阶API改下沉模式：840imgs/sec)

使用低阶API模式训练，用户可以自己控制哪些数据输入网络。

for epoch in range(epoch_max):

        print("\nEpoch:", epoch+1, "/", epoch_max)

        t_start = time.time()

        train_loss = 0

        train_correct = 0

        train_total = 0

        for _, (data, gt_classes, _) in enumerate(ds_train):

            model.set_train()

            # 向网络中传入图片数据和标签

            loss, output = model(data, gt_classes)

            train_loss += loss

            correct = correct_num(output, gt_classes)

            correct = correct.asnumpy()

            train_correct += correct.sum()

            cb_params.cur_step_num += 1

            ckpoint_cb.step_end(run_context)

低阶API模式改下沉后，则会将整个dataset输入网络，不能控制哪些数据输入网络，则需将dataset输出和network输入匹配。若不匹配则会报错。

错误情形1：dataset输出多于network输入

dataset输出为：input_data、label和flag。而网络中需输入input_data和label。

class Dataset: def __init__(self, image_list, label_list): super(Dataset, self).__init__() self.imgs = image_list self.labels = label_list def __getitem__(self, index): img = Image.open(self.imgs[index]).convert('RGB') flag = self.labels[index] return img, self.labels[index], flag def __len__(self): return len(self.imgs) def create_dataset(data_path, do_train, batch_size, repeat_num=1): dataset = Dataset(save_image_list, save_label_list) sampler = MySampler(dataset) print("sample") cifar_ds = ds.GeneratorDataset(dataset, column_names=["image", "label", "flag"], sampler=sampler, shuffle=True) steps_per_epoch = cifar_ds.get_dataset_size() cifar_ds = cifar_ds.repeat(repeat_num) return cifar_ds, steps_per_epoch ds_train, steps_per_epoch_train = create_dataset(data_path, do_train=True, batch_size=train_batch_size, repeat_num=1) model.train(epoch_max, ds_train, callbacks=[ckpoint_cb, LossMonitor(), fps], dataset_sink_mode=sink_mode, sink_size=steps_per_epoch_train)

将会出现如下报错：

[ERROR] ANALYZER(26833,python):2021-07-15-07:03:21.469.703 [mindspore/ccsrc/pipeline/jit/static_analysis/evaluator.cc:74] Eval] Function construct, The number of parameters of this function is 2, but the number of provided arguments is 3. NodeInfo: In file MindSpore_1P_definedata_high.py(35) def construct(self, input_data, label): ^ Traceback (most recent call last): File "MindSpore_1P_definedata_high.py", line 344, in VAL_BATCH_SIZE, REPEAT_SIZE, dataset_sink_mode) File "MindSpore_1P_definedata_high.py", line 279, in train_net dataset_sink_mode=sink_mode, sink_size=steps_per_epoch_train) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/model.py", line 627, in train sink_size=sink_size) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/model.py", line 413, in _train self._train_dataset_sink_process(epoch, train_dataset, list_callback, cb_params, sink_size) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/model.py", line 475, in _train_dataset_sink_process outputs = self._train_network(*inputs) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/nn/cell.py", line 341, in __call__ out = self.compile_and_run(*inputs) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/nn/cell.py", line 608, in compile_and_run self.compile(*inputs) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/nn/cell.py", line 595, in compile _executor.compile(self, *inputs, phase=self.phase, auto_parallel_mode=self._auto_parallel_mode) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/common/api.py", line 494, in compile result = self._executor.compile(obj, args_list, phase, use_vm) TypeError: mindspore/ccsrc/pipeline/jit/static_analysis/evaluator.cc:74 Eval] Function construct, The number of parameters of this function is 2, but the number of provided arguments is 3. NodeInfo: In file MindSpore_1P_definedata_high.py(35) def construct(self, input_data, label): ^ The function call stack (See file 'analyze_fail.dat' for details):# 0 In file /home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/dataset_helper.py(75) return self.network(*outputs) ^# 1 In file MindSpore_1P_definedata_high.py(56) loss = self.network(*inputs)

错误情形2：dataset输出少于network输入

dataset输出为：input_data。而网络中需输入input_data和label。

class Dataset: def __init__(self, image_list, label_list): super(Dataset, self).__init__() self.imgs = image_list self.labels = label_list def __getitem__(self, index): img = Image.open(self.imgs[index]).convert('RGB') return img def __len__(self): return len(self.imgs) def create_dataset(data_path, do_train, batch_size, repeat_num=1): dataset = Dataset(save_image_list, save_label_list) sampler = MySampler(dataset) print("sample") cifar_ds = ds.GeneratorDataset(dataset, column_names=["image"], sampler=sampler, shuffle=True) steps_per_epoch = cifar_ds.get_dataset_size() cifar_ds = cifar_ds.repeat(repeat_num) return cifar_ds, steps_per_epoch ds_train, steps_per_epoch_train = create_dataset(data_path, do_train=True, batch_size=train_batch_size, repeat_num=1) model.train(epoch_max, ds_train, callbacks=[ckpoint_cb, LossMonitor(), fps], dataset_sink_mode=sink_mode, sink_size=steps_per_epoch_train)

将会出现如下报错：

Traceback (most recent call last): File "MindSpore_1P_definedata_high.py", line 344, in VAL_BATCH_SIZE, REPEAT_SIZE, dataset_sink_mode) File "MindSpore_1P_definedata_high.py", line 279, in train_net dataset_sink_mode=sink_mode, sink_size=steps_per_epoch_train) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/model.py", line 627, in train sink_size=sink_size) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/model.py", line 413, in _train self._train_dataset_sink_process(epoch, train_dataset, list_callback, cb_params, sink_size) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/model.py", line 466, in _train_dataset_sink_process dataset_helper=dataset_helper) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/model.py", line 292, in _exec_preprocess dataset_helper = DatasetHelper(dataset, dataset_sink_mode, sink_size, epoch_num) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/dataset_helper.py", line 218, in __init__ self.iter = iterclass(dataset, sink_size, epoch_num) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/dataset_helper.py", line 360, in __init__ super().__init__(dataset, sink_size, epoch_num) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/dataset_helper.py", line 268, in __init__ create_data_info_queue=create_data_info_queue) File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/train/_utils.py", line 59, in _exec_datagraph batch_size = exec_dataset.get_batch_size() File "/home/ma-user/miniconda3/envs/MindSpore-python3.7-aarch64/lib/python3.7/site-packages/mindspore/dataset/engine/datasets.py", line 1567, in get_batch_size self._batch_size = runtime_getter[0].GetBatchSize() RuntimeError: Thread ID 281473819629872 Unexpected error. input column name: label doesn't exist in the dataset columns. Line of code : 366 File : /home/jenkins/agent-working-dir/workspace/Compile_Ascend_ARM_EulerOS/mindspore/mindspore/ccsrc/minddata/dataset/engine/datasetops/map_op/map_op.cc

定义多Loss输出的网络结构

背景信息

有的任务需要同时训练多个Loss，比如检测任务，这时需要同时输出多个Loss的值方便查看各个Loss的趋势。

经验总结

MindSpore默认只支持单Loss的输出，如果要同时输出多个Loss需要重写TrainOneStepCell函数（原本MindSpore的内置函数），主要重写部分为construct中关于梯度计算的部分。 具体代码如下所示：

class TrainOneStepCell(nn.Cell): def __init__(self, network, optimizer, sens=1.0): super(TrainOneStepCell, self).__init__(auto_prefix=False) self.network = network self.network.add_flags(defer_inline=True) self.weights = ParameterTuple(network.trainable_params()) self.optimizer = optimizer self.grad = C.GradOperation('grad', get_by_list=True, sens_param=True) self.sens = sens self.reducer_flag = False self.grad_reducer = None parallel_mode = _get_parallel_mode() if parallel_mode in (ParallelMode.DATA_PARALLEL, ParallelMode.HYBRID_PARALLEL): self.reducer_flag = True if self.reducer_flag: mean = _get_mirror_mean() degree = _get_device_num() self.grad_reducer = DistributedGradReducer(optimizer.parameters, mean, degree) def construct(self, data, label): weights = self.weights loss1, loss2 = self.network(data, label) sens1 = P.Fill()(P.DType()(loss1), P.Shape()(loss1), self.sens) sens2 = P.Fill()(P.DType()(loss2), P.Shape()(loss2), self.sens) sens = (sens1, sens2) grads = self.grad(self.network, weights)(data, label, sens) if self.reducer_flag: # apply grad reducer on grads grads = self.grad_reducer(grads) return F.depend(loss1, self.optimizer(grads)), F.depend(loss2, self.optimizer(grads))

详细代码请前往MindSpore论坛进行下载：https://bbs.huaweicloud.com/forum/thread-0221980893779600015-1-1.html