Create output dir in training.Loop if it's not there (same as Trainer). Also report training loss in Loop.

PiperOrigin-RevId: 319320458

Author: Lukasz Kaiser

trax/fastmath/jax.py

@@ -418,6 +418,7 @@ def _custom_grad(f_vjp, f_original):
     'erf': jax_special.erf,
     'expit': jax_special.expit,
     'grad': jax.grad,
+    'value_and_grad': jax.value_and_grad,
     'jit': jax.jit,
     'logsumexp': jax_special.logsumexp,
     'lt': lax.lt,

trax/fastmath/ops.py

@@ -164,6 +164,26 @@ def grad(*args, **kwargs):
   return backend()['grad'](*args, **kwargs)
 
 
+def value_and_grad(*args, **kwargs):
+  """Computes the gradient of the specified function together with the value."""
+  if 'value_and_grad' in backend():
+    return backend()['value_and_grad'](*args, **kwargs)
+  grad_fn = grad(*args, **kwargs)
+  fn = args[0]
+  has_aux = False
+  if has_aux in kwargs:
+    has_aux = kwargs['has_aux']
+  if not has_aux:
+    def val_and_grad(*fn_args, **fn_kwargs):
+      return fn(*fn_args, **fn_kwargs), grad_fn(*fn_args, **fn_kwargs)
+    return val_and_grad
+  def val_and_grad_aux(*fn_args, **fn_kwargs):
+    g, aux = grad_fn(*fn_args, **fn_kwargs)
+    res, _ = fn(*fn_args, **fn_kwargs)
+    return (res, aux), g
+  return val_and_grad_aux
+
+
 def vjp(*args, **kwargs):
   """Computes the vector-Jacobian product for the specified function."""
   return backend()['vjp'](*args, **kwargs)

trax/supervised/training.py

@@ -103,7 +103,11 @@ def __init__(self, model, task, eval_model=None, eval_task=None,
     self._model_in_training = tl.Serial(model, task.loss_layer)
     self._eval_model = model if eval_model is None else eval_model
     self._eval_task = eval_task
+    self._rjust_len = max([0] + [len(name) for name in eval_task.metric_names])
+
     self._output_dir = os.path.expanduser(output_dir) if output_dir else None
+    if output_dir is not None:
+      tf.io.gfile.makedirs(output_dir)
     default_fn = _at_step_1_and_periodically_at(task.n_steps_per_checkpoint)
     self._checkpoint_at = checkpoint_at or default_fn
     self._eval_at = eval_at or default_fn
@@ -120,9 +124,10 @@ def __init__(self, model, task, eval_model=None, eval_task=None,
     _, _ = task.optimizer.tree_init(self._model_in_training.weights)
 
     self._gradients_and_state_fn = (
-        fastmath.jit(fastmath.grad(self._model_in_training.pure_fn,
-                                   argnums=1,  # arg1 of pure_fn: weights
-                                   has_aux=True)))  # return (gradients, state)
+        fastmath.jit(fastmath.value_and_grad(
+            self._model_in_training.pure_fn,
+            argnums=1,  # arg1 of pure_fn: weights
+            has_aux=True)))  # return (loss, state), gradients
 
     if eval_task is not None:
       model_with_metrics = _model_with_metrics(self._eval_model, eval_task)
@@ -142,13 +147,23 @@ def run(self, n_steps=1):
     weights = self._model_in_training.weights
     state = self._model_in_training.state
     slots = self._task.optimizer.slots
+    loss_acc, step_acc = 0.0, 0
     for _ in range(n_steps):
       self._step += 1
-      weights, state, slots = self._run_one_step(weights, state, slots)
+      loss, weights, state, slots = self._run_one_step(weights, state, slots)
+      loss_acc += loss
+      step_acc += 1
       if self._eval_at(self._step):
         self._model_in_training.weights = weights
         self._model_in_training.state = state
         self._eval_model.weights = self._model.weights
+        # TODO(lukaszkaiser): move this to a better place with other reporting
+        loss_name = self._task.loss_layer.name
+        step_acc = max(1, step_acc)  # only here do avoid potential divide-by-0
+        self._log_step('%s %s | % .8f' % (
+            'train'.ljust(5), loss_name.rjust(self._rjust_len),
+            loss_acc / float(step_acc)))
+        loss_acc, step_acc = 0.0, 0
         self.run_evals(weights, state)
       if self._checkpoint_at(self._step):
         self.save_checkpoint(weights, state, slots)
@@ -199,11 +214,11 @@ def _run_one_step(self, weights, state, slots):
     opt_params = optimizer._init_opt_params  # pylint: disable=protected-access
     opt_params.update({'learning_rate': self._task.learning_rate(step)})
 
-    gradients, updated_state = (
+    (loss, updated_state), gradients = (
         self._gradients_and_state_fn(batch, weights, state, self.new_rng()))
     updated_weights, updated_slots, _ = (
         optimizer.tree_update(step, gradients, weights, slots, opt_params))
-    return updated_weights, updated_state, updated_slots
+    return loss, updated_weights, updated_state, updated_slots
 
   def run_evals(self, weights=None, state=None):
     """Runs and records evals for this training session.
@@ -230,10 +245,9 @@ def run_evals(self, weights=None, state=None):
           self._metrics_fn(batch, metrics_weights, metrics_state, rng))
       sums += metric_values
     averages = sums / n_batches
-    rjust_len = max([0] + [len(name) for name in eval_task.metric_names])
     for name, average_value in zip(eval_task.metric_names, averages):
       self._log_step('%s %s | % .8f' % (
-          'eval'.ljust(5), name.rjust(rjust_len), average_value))
+          'eval'.ljust(5), name.rjust(self._rjust_len), average_value))
 
   def _log_step(self, msg):
     """Logs message, labeled with the current training step number."""