Add inference support for BERT. (#5199)

* Add inference support for BERT.

* Update inference support for BERT.

PaddleNLP/examples/language_model/bert/README.md

@@ -138,3 +138,38 @@ python -u ./run_glue.py \
 | QQP   | Accuracy/F1                  |  0.90581/0.87347  |
 | MNLI  | Matched acc/MisMatched acc   |  0.84422/0.84825  |
 | RTE   | Accuracy                     |      0.711191     |
+
+
+### 预测
+
+在Fine-tuning完成后，我们可以使用如下方式导出希望用来预测的模型：
+
+```shell
+python -u ./export_model.py \
+    --model_type bert \
+    --model_path bert-base-uncased \
+    --output_path ./infer_model/model
+```
+
+其中参数释义如下：
+- `model_type` 指示了模型类型，使用BERT模型时设置为bert即可。
+- `model_path` 表示训练模型的保存路径，与训练时的`output_dir`一致。
+- `output_path` 表示导出预测模型文件的前缀。保存时会添加后缀（`pdiparams`，`pdiparams.info`，`pdmodel`）；除此之外，还会在`model_path`包含的目录下保存tokenizer相关内容。
+
+然后按照如下的方式进行GLUE中的评测任务进行预测（基于Paddle的[Python预测API](https://www.paddlepaddle.org.cn/documentation/docs/zh/2.0-rc1/guides/05_inference_deployment/inference/python_infer_cn.html)）：
+
+```shell
+python -u ./predict_glue.py \
+    --task_name SST-2 \
+    --model_type bert \
+    --model_path ./infer_model/model \
+    --batch_size 32 \
+    --max_seq_length 128
+```
+
+其中参数释义如下：
+- `task_name` 表示Fine-tuning的任务。
+- `model_type` 指示了模型类型，使用BERT模型时设置为bert即可。
+- `model_path` 表示预测模型文件的前缀，和上一步导出预测模型中的`output_path`一致。
+- `batch_size` 表示每个预测批次的样本数目。
+- `max_seq_length` 表示最大句子长度，超过该长度将被截断。

PaddleNLP/examples/language_model/bert/export_model.py

+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import argparse
+import os
+
+import paddle
+
+from run_glue import MODEL_CLASSES
+
+
+def parse_args():
+    parser = argparse.ArgumentParser()
+
+    # Required parameters
+    parser.add_argument(
+        "--model_type",
+        default=None,
+        type=str,
+        required=True,
+        help="Model type selected in the list: " +
+        ", ".join(MODEL_CLASSES.keys()),
+    )
+    parser.add_argument(
+        "--model_path",
+        default=None,
+        type=str,
+        required=True,
+        help="Path of the trained model to be exported.",
+    )
+    parser.add_argument(
+        "--output_path",
+        default=None,
+        type=str,
+        required=True,
+        help=
+        "The output file prefix used to save the exported inference model.",
+    )
+    args = parser.parse_args()
+    return args
+
+
+def main():
+    args = parse_args()
+
+    args.model_type = args.model_type.lower()
+    model_class, tokenizer_class = MODEL_CLASSES[args.model_type]
+
+    # build model and load trained parameters
+    model = model_class.from_pretrained(args.model_path)
+    # switch to eval model
+    model.eval()
+    # convert to static graph with specific input description
+    model = paddle.jit.to_static(
+        model,
+        input_spec=[
+            paddle.static.InputSpec(shape=[None, None],
+                                    dtype="int64"),  # input_ids
+            paddle.static.InputSpec(shape=[None, None],
+                                    dtype="int64")  # segment_ids
+        ])
+    # save converted static graph model
+    paddle.jit.save(model, args.output_path)
+    # also save tokenizer for inference usage
+    tokenizer = tokenizer_class.from_pretrained(args.model_path)
+    tokenizer.save_pretrained(os.path.dirname(args.output_path))
+
+
+if __name__ == "__main__":
+    main()

PaddleNLP/examples/language_model/bert/prdict_glue.py

+# Copyright (c) 2020 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import argparse
+import os
+from functools import partial
+
+import paddle
+from paddle import inference
+from paddlenlp.data import Stack, Tuple, Pad
+
+from run_glue import convert_example, TASK_CLASSES, MODEL_CLASSES
+
+
+def parse_args():
+    parser = argparse.ArgumentParser()
+
+    # Required parameters
+    parser.add_argument(
+        "--task_name",
+        default=None,
+        type=str,
+        required=True,
+        help="The name of the task to perform predict, selected in the list: " +
+        ", ".join(TASK_CLASSES.keys()),
+    )
+    parser.add_argument(
+        "--model_type",
+        default=None,
+        type=str,
+        required=True,
+        help="Model type selected in the list: " +
+        ", ".join(MODEL_CLASSES.keys()),
+    )
+    parser.add_argument(
+        "--model_path",
+        default=None,
+        type=str,
+        required=True,
+        help="The path prefix of inference model to be used.",
+    )
+    parser.add_argument(
+        "--select_device",
+        default="gpu",
+        choices=["gpu", "cpu", "xpu"],
+        help="Device selected for inference.",
+    )
+    parser.add_argument(
+        "--batch_size",
+        default=32,
+        type=int,
+        help="Batch size for predict.",
+    )
+    parser.add_argument(
+        "--max_seq_length",
+        default=128,
+        type=int,
+        help=
+        "The maximum total input sequence length after tokenization. Sequences longer "
+        "than this will be truncated, sequences shorter will be padded.",
+    )
+    args = parser.parse_args()
+    return args
+
+
+class Predictor(object):
+    def __init__(self, predictor, input_handles, output_handles):
+        self.predictor = predictor
+        self.input_handles = input_handles
+        self.output_handles = output_handles
+
+    @classmethod
+    def create_predictor(cls, args):
+        config = paddle.inference.Config(args.model_path + ".pdmodel",
+                                         args.model_path + ".pdiparams")
+        if args.select_device == "gpu":
+            # set GPU configs accordingly
+            config.enable_use_gpu(100, 0)
+        elif args.select_device == "cpu":
+            # set CPU configs accordingly,
+            # such as enable_mkldnn, set_cpu_math_library_num_threads
+            config.disable_gpu()
+        elif args.select_device == "xpu":
+            # set XPU configs accordingly
+            config.enable_xpu(100)
+        config.switch_use_feed_fetch_ops(False)
+        predictor = paddle.inference.create_predictor(config)
+        input_handles = [
+            predictor.get_input_handle(name)
+            for name in predictor.get_input_names()
+        ]
+        output_handles = [
+            predictor.get_input_handle(name)
+            for name in predictor.get_output_names()
+        ]
+        return cls(predictor, input_handles, output_handles)
+
+    def predict_batch(self, data):
+        for input_field, input_handle in zip(data, self.input_handles):
+            input_handle.copy_from_cpu(input_field.numpy(
+            ) if isinstance(input_field, paddle.Tensor) else input_field)
+        self.predictor.run()
+        output = [
+            output_handle.copy_to_cpu() for output_handle in self.output_handles
+        ]
+        return output
+
+    def predict(self, dataset, collate_fn, batch_size=1):
+        batch_sampler = paddle.io.BatchSampler(dataset,
+                                               batch_size=batch_size,
+                                               shuffle=False)
+        data_loader = paddle.io.DataLoader(dataset=dataset,
+                                           batch_sampler=batch_sampler,
+                                           collate_fn=collate_fn,
+                                           num_workers=0,
+                                           return_list=True)
+        outputs = []
+        for data in data_loader:
+            output = self.predict_batch(data)
+            outputs.append(output)
+        return outputs
+
+
+def main():
+    args = parse_args()
+
+    predictor = Predictor.create_predictor(args)
+
+    args.task_name = args.task_name.lower()
+    dataset_class, metric_class = TASK_CLASSES[args.task_name]
+    args.model_type = args.model_type.lower()
+    model_class, tokenizer_class = MODEL_CLASSES[args.model_type]
+
+    dataset = dataset_class.get_datasets("test")
+    tokenizer = tokenizer_class.from_pretrained(os.path.dirname(
+        args.model_path))
+    transform_fn = partial(convert_example,
+                           tokenizer=tokenizer,
+                           label_list=dataset.get_labels(),
+                           max_seq_length=args.max_seq_length,
+                           is_test=True)
+    batchify_fn = lambda samples, fn=Tuple(
+        Pad(axis=0, pad_val=tokenizer.pad_token_id),  # input
+        Pad(axis=0, pad_val=tokenizer.pad_token_id),  # segment
+        Stack(),  # length
+    ): [data for i, data in enumerate(fn(samples)) if i != 2]
+    dataset = dataset.apply(transform_fn)
+
+    predictor.predict(dataset,
+                      batch_size=args.batch_size,
+                      collate_fn=batchify_fn)
+
+
+if __name__ == "__main__":
+    main()