Fix bugs in Executor (#306)

* Fix: saved `meta_dict` contains excessive data

- `meta_dict` contains training and evaluation metrics objects, but it's
  unnecessary to save objects -- only their values are needed.
- A more serious problem is with the `LR` metric, which stores a
  reference to the optimizer. This will result in the entire optimizer
  being saved in the meta-info.
- Solution is two parts: 1) save only the metric values; 2) store the
  optimizer as a weakref.

* Fix: don't close files when calling test in train

- `_open_files` and `_close_files` are called at the beginning and end
  of `train` and `test`, to prevent holding on to an open file object
  for an unnecessarily long amount of time.
- However, it's possible that we call `test` within `train`. For
  instance, calling `test` in a action triggered by the validation
  event. In this case, the file will be closed before training ends.
- Solution is to check whether we need to open files, and if we don't,
  then don't open nor close them.

* Fix: missing call to tracker in `_validate_loop`

This is so stupid: for some reason I forgot to call `_valid_tracker.add`
in `_validate_loop`, so the status is never updated during validation.

* Revert c89e0e4: fix `meta_dict` issue

- It turns out we must store the metric objects -- otherwise we can't
  even compare two metric values.
- So I just changed the pickle behavior for `LR` so that it doesn't save
  the optimizer. Seems like a hack, but let's just leave it at this.

* Fix doc building issues

docs/code/data.rst

@@ -132,9 +132,6 @@ Data Loaders
 .. autoclass:: texar.torch.data.DatasetBase
     :members:
 
-    .. automethod:: process
-    .. automethod:: collate
-
 :hidden:`MonoTextData`
 ~~~~~~~~~~~~~~~~~~~~~~~~
 .. autoclass:: texar.torch.data.MonoTextData

tests/run/executor_test.py

@@ -99,6 +99,7 @@ def tearDown(self) -> None:
         shutil.rmtree(self.tbx_logging_dir)
 
     def test_train_loop(self):
+        optimizer = torch.optim.Adam(self.model.parameters())
         executor = Executor(
             model=self.model,
             train_data=self.datasets["train"],
@@ -110,8 +111,9 @@ def test_train_loop(self):
             save_every=[cond.time(seconds=10), cond.validation(better=True)],
             train_metrics=[("loss", metric.RunningAverage(20)),
                            metric.F1(pred_name="preds", mode="macro"),
-                           metric.Accuracy(pred_name="preds")],
-            optimizer={"type": torch.optim.Adam, "kwargs": {}},
+                           metric.Accuracy(pred_name="preds"),
+                           metric.LR(optimizer)],
+            optimizer=optimizer,
             stop_training_on=cond.epoch(10),
             valid_metrics=[metric.F1(pred_name="preds", mode="micro"),
                            ("loss", metric.Average())],
@@ -129,6 +131,9 @@ def test_train_loop(self):
         executor.train()
         executor.test()
 
+        executor.save()
+        executor.load()
+
     def test_tbx_logging(self):
         executor = Executor(
             model=self.model,

texar/torch/run/executor.py

@@ -1280,8 +1280,12 @@ def remove_action(self) -> None:
     def train(self):
         r"""Start the training loop.
         """
-        # open the log files
-        self._open_files()
+        # Check whether files have been opened, to avoid re-opening and closing.
+        # This could happen when, e.g., `test` is called in a registered hook
+        # during training.
+        should_open_file = (len(self._opened_files) == 0)
+        if should_open_file:
+            self._open_files()
 
         if self._directory_exists:
             self.write_log(
@@ -1351,8 +1355,9 @@ def _try_get_data_size(executor: 'Executor'):
 
         self._fire_event(Event.Training, True)
 
-        # close the log files
-        self._close_files()
+        # Close the log files if we opened them here.
+        if should_open_file:
+            self._close_files()
 
     def test(self, dataset: OptionalDict[DatasetBase] = None):
         r"""Start the test loop.
@@ -1369,8 +1374,12 @@ def test(self, dataset: OptionalDict[DatasetBase] = None):
                 If `None`, :attr:`test_data` from the constructor arguments is
                 used. Defaults to `None`.
         """
-        # open the log files
-        self._open_files()
+        # Check whether files have been opened, to avoid re-opening and closing.
+        # This could happen when, e.g., `test` is called in a registered hook
+        # during training.
+        should_open_file = (len(self._opened_files) == 0)
+        if should_open_file:
+            self._open_files()
 
         if dataset is None and self.test_data is None:
             raise ValueError("No testing dataset is specified")
@@ -1417,8 +1426,9 @@ def test(self, dataset: OptionalDict[DatasetBase] = None):
 
         self.model.train(model_mode)
 
-        # close the log files
-        self._close_files()
+        # Close the log files if we opened them here.
+        if should_open_file:
+            self._close_files()
 
     def _register_logging_actions(self, show_live_progress: List[str]):
         # Register logging actions.
@@ -1728,6 +1738,7 @@ def _open_files(self):
     def _close_files(self):
         for file in self._opened_files:
             file.close()
+        self._opened_files = []
 
         if hasattr(self, 'summary_writer'):
             self.summary_writer.close()
@@ -1890,7 +1901,7 @@ def _validate_loop(self, iterator: DataIterator) -> None:
             self._fire_event(Event.ValidationIteration, False)
             return_dict = self._validate_step(batch)
 
-            # Update metrics.
+            self._valid_tracker.add(len(batch))
             utils.update_metrics(return_dict, batch, self.valid_metrics)
 
             self._fire_event(Event.ValidationIteration, True)
@@ -1906,8 +1917,7 @@ def _test_loop(self, iterator: DataIterator) -> None:
             return_dict = self._test_step(batch)
 
             self._test_tracker.add(len(batch))
-            utils.update_metrics(
-                return_dict, batch, self.test_metrics)
+            utils.update_metrics(return_dict, batch, self.test_metrics)
 
             self._fire_event(Event.TestingIteration, True)
 

texar/torch/run/metric/summary.py

@@ -17,6 +17,7 @@
 
 from collections import deque
 from typing import Any, Deque, Optional, Sequence
+import weakref
 
 import numpy as np
 from torch.optim.optimizer import Optimizer
@@ -152,15 +153,25 @@ class LR(StreamingMetric[Any, float]):
 
     def __init__(self, optimizer: Optimizer, param_group: int = 0):
         super().__init__(pred_name=None)
-        self.optimizer = optimizer
+        self.optimizer = weakref.ref(optimizer)
         self.group = param_group
 
     def add(self, _, __):
         pass
 
     def value(self) -> float:
-        return self.optimizer.param_groups[self.group]['lr']  # type: ignore
+        return self.optimizer().param_groups[self.group]['lr']  # type: ignore
 
     def better(self, cur: float, prev: float) -> Optional[bool]:
         # Always return `None` to indicate values are uncomparable.
         return None
+
+    def __getstate__(self):
+        # There's no point in pickling an `LR` metric; just ignore it.
+        return None
+
+    def __getnewargs__(self):
+        # But when unpickling, we need to make sure we can construct something.
+        # This requires passing a dummy `optimizer` to which a weakref can be
+        # constructed. In this case, we use an arbitrary built-in class.
+        return (int,)