allow specifying max_tokens for generation (#280)

* allow specifying max_tokens for generation

fairseq/options.py

@@ -106,7 +106,7 @@ def add_dataset_args(parser, train=False, gen=False):
                        help='max number of tokens in the target sequence')
     group.add_argument('--skip-invalid-size-inputs-valid-test', action='store_true',
                        help='Ignore too long or too short lines in valid and test set')
-    group.add_argument('--max-tokens', default=6000, type=int, metavar='N',
+    group.add_argument('--max-tokens', type=int, metavar='N',
                        help='maximum number of tokens in a batch')
     group.add_argument('--max-sentences', '--batch-size', type=int, metavar='N',
                        help='maximum number of sentences in a batch')

generate.py

@@ -16,6 +16,10 @@
 
 def main(args):
     assert args.path is not None, '--path required for generation!'
+
+    if args.max_tokens is None and args.max_sentences is None:
+        args.max_tokens = 12000
+
     print(args)
     assert not args.sampling or args.nbest == args.beam, \
         '--sampling requires --nbest to be equal to --beam'
@@ -58,12 +62,13 @@ def main(args):
     # Load alignment dictionary for unknown word replacement
     # (None if no unknown word replacement, empty if no path to align dictionary)
     align_dict = utils.load_align_dict(args.replace_unk)
-
     # Load dataset (possibly sharded)
     max_positions = min(model.max_encoder_positions() for model in models)
+
     itr = dataset.eval_dataloader(
         args.gen_subset,
-        max_sentences=args.max_sentences or 128,
+        max_tokens=args.max_tokens,
+        max_sentences=args.max_sentences,
         max_positions=max_positions,
         skip_invalid_size_inputs_valid_test=args.skip_invalid_size_inputs_valid_test,
     )

train.py

@@ -18,6 +18,10 @@
 
 
 def main(args):
+
+    if args.max_tokens is None:
+        args.max_tokens = 6000
+
     print(args)
 
     if not torch.cuda.is_available():