Internal change

PiperOrigin-RevId: 347480509

official/core/base_trainer.py

@@ -301,6 +301,7 @@ class Trainer(orbit.StandardTrainer, orbit.StandardEvaluator):
     def step_fn(inputs):
       logs = self.task.validation_step(
           inputs, model=self.model, metrics=self.validation_metrics)
+      if self.task.loss in logs:
         self._validation_loss.update_state(logs[self.task.loss])
       return logs
 
@@ -311,8 +312,14 @@ class Trainer(orbit.StandardTrainer, orbit.StandardEvaluator):
   def eval_end(self, aggregated_logs=None):
     """Processes evaluation results."""
     logs = {}
-    for metric in self.validation_metrics + [self.validation_loss]:
+    for metric in self.validation_metrics:
       logs[metric.name] = metric.result()
+    if self.validation_loss.count.numpy() != 0:
+      logs[self.validation_loss.name] = self.validation_loss.result()
+    else:
+      # `self.validation_loss` metric was not updated, because the validation
+      # loss was not returned from the task's `validation_step` method.
+      logging.info("The task did not report validation loss.")
     if aggregated_logs:
       metrics = self.task.reduce_aggregated_logs(aggregated_logs)
       logs.update(metrics)

official/core/base_trainer_test.py

@@ -54,8 +54,8 @@ class TrainerTest(tf.test.TestCase, parameterized.TestCase):
                 }
             })))
 
-  def create_test_trainer(self, config, model_dir=None):
-    task = mock_task.MockTask(config.task, logging_dir=model_dir)
+  def create_test_trainer(self, config, model_dir=None, task=None):
+    task = task or mock_task.MockTask(config.task, logging_dir=model_dir)
     ckpt_exporter = train_lib.maybe_create_best_ckpt_exporter(config, model_dir)
     trainer = trainer_lib.Trainer(
         config,
@@ -79,6 +79,25 @@ class TrainerTest(tf.test.TestCase, parameterized.TestCase):
       trainer = self.create_test_trainer(self._config)
       logs = trainer.evaluate(tf.convert_to_tensor(5, dtype=tf.int32))
       self.assertEqual(logs['counter'], 5. * distribution.num_replicas_in_sync)
+      self.assertIn('validation_loss', logs)
+
+  @combinations.generate(all_strategy_combinations())
+  def test_trainer_validate_without_loss(self, distribution):
+
+    class MockTaskWithoutValidationLoss(mock_task.MockTask):
+
+      def validation_step(self, inputs, model, metrics=None):
+        # Disable validation loss.
+        logs = super().validation_step(inputs, model)
+        del logs[self.loss]
+        return logs
+
+    with distribution.scope():
+      task = MockTaskWithoutValidationLoss()
+      trainer = self.create_test_trainer(self._config, task=task)
+      logs = trainer.evaluate(tf.convert_to_tensor(5, dtype=tf.int32))
+      self.assertEqual(logs['counter'], 5. * distribution.num_replicas_in_sync)
+      self.assertNotIn('validation_loss', logs)
 
   @combinations.generate(
       combinations.combine(

official/nlp/tasks/question_answering.py

@@ -212,7 +212,10 @@ class QuestionAnsweringTask(base_task.Task):
         input_context)
 
   def build_metrics(self, training=None):
-    del training
+    if not training:
+      # We cannot compute start/end_position_accuracy because start/end_position
+      # labels are not available in the validation dataset (b/173794928).
+      return []
     # TODO(lehou): a list of metrics doesn't work the same as in compile/fit.
     metrics = [
         tf.keras.metrics.SparseCategoricalAccuracy(
@@ -244,8 +247,9 @@ class QuestionAnsweringTask(base_task.Task):
     unique_ids = features.pop('unique_ids')
     model_outputs = self.inference_step(features, model)
     start_logits, end_logits = model_outputs
+    # We cannot compute validation_loss here, because start/end_position
+    # labels are not available in the validation dataset (b/173794928).
     logs = {
-        self.loss: 0.0,  # TODO(lehou): compute the real validation loss.
         'unique_ids': unique_ids,
         'start_logits': start_logits,
         'end_logits': end_logits,
@@ -293,8 +297,6 @@ class QuestionAnsweringTask(base_task.Task):
     if self.task_config.validation_data.version_2_with_negative:
       eval_metrics = squad_evaluate_v2_0.evaluate(pred_dataset, all_predictions,
                                                   scores_diff)
-      # Filter out useless metrics, such as start_position_accuracy that
-      # we did not actually compute.
       eval_metrics = {
           'exact_match': eval_metrics['final_exact'],
           'exact_match_threshold': eval_metrics['final_exact_thresh'],
@@ -305,8 +307,6 @@ class QuestionAnsweringTask(base_task.Task):
       }
     else:
       eval_metrics = squad_evaluate_v1_1.evaluate(pred_dataset, all_predictions)
-      # Filter out useless metrics, such as start_position_accuracy that
-      # we did not actually compute.
       eval_metrics = {
           'exact_match': eval_metrics['exact_match'],
           'final_f1': eval_metrics['final_f1']
@@ -417,7 +417,6 @@ class XLNetQuestionAnsweringTask(QuestionAnsweringTask):
     class_logits = model_outputs['class_logits']
 
     logs = {
-        self.loss: 0.0,  # TODO(lehou): compute the real validation loss.
         'unique_ids': unique_ids,
         'start_top_predictions': start_top_predictions,
         'end_top_predictions': end_top_predictions,

official/nlp/tasks/question_answering_test.py

@@ -250,6 +250,7 @@ class XLNetQuestionAnsweringTaskTest(tf.test.TestCase, parameterized.TestCase):
     logs = task.aggregate_logs(step_outputs=logs)
     metrics = task.reduce_aggregated_logs(logs)
     self.assertIn("final_f1", metrics)
+    self.assertNotIn("loss", metrics)
 
   def test_task(self):
     config = question_answering.XLNetQuestionAnsweringConfig(