[Fix] seq2seq pack_dataset.py actually packs (#5913)

Huge MT speedup!

examples/seq2seq/pack_dataset.py

@@ -16,13 +16,14 @@ from transformers import AutoTokenizer
 def pack_examples(tok, src_examples, tgt_examples, max_tokens=1024):
 
     finished_src, finished_tgt = [], []
-    new_src, new_tgt = "", ""
+
     sorted_examples = list(sorted(zip(src_examples, tgt_examples), key=lambda x: len(x[0])))
+    new_src, new_tgt = sorted_examples[0]
 
     def is_too_big(strang):
         return tok(strang, return_tensors="pt").input_ids.shape[1] > max_tokens
 
-    for src, tgt in tqdm(sorted_examples):
+    for src, tgt in tqdm(sorted_examples[1:]):
         cand_src = new_src + " " + src
         cand_tgt = new_tgt + " " + tgt
         if is_too_big(cand_src) or is_too_big(cand_tgt):  # cant fit, finalize example
@@ -31,21 +32,37 @@ def pack_examples(tok, src_examples, tgt_examples, max_tokens=1024):
             new_src, new_tgt = src, tgt
         else:  # can fit, keep adding
             new_src, new_tgt = cand_src, cand_tgt
+        # import ipdb; ipdb.set_trace()
 
+    # cleanup
+    if new_src:
+        assert new_tgt
+        finished_src.append(new_src)
+        finished_tgt.append(new_tgt)
     return finished_src, finished_tgt
 
 
+def minify(src_dir: Path, dest_dir: Path, n: int):
+    """Write first n lines of each file f in src_dir to dest_dir/f"""
+    dest_dir.mkdir(exist_ok=True)
+    for path in src_dir.iterdir():
+        new = [x.rstrip() for x in list(path.open().readlines())][:n]
+        dest_path = dest_dir.joinpath(path.name)
+        print(dest_path)
+        dest_path.open("w").write("\n".join(new))
+
+
 def pack_data_dir(tok, data_dir: Path, max_tokens, save_path):
     save_path = Path(save_path)
     save_path.mkdir(exist_ok=True)
     for split in ["val", "test", "train"]:
         src_path, tgt_path = data_dir / f"{split}.source", data_dir / f"{split}.target"
-        src_docs = list(Path(src_path).open().readlines())
-        tgt_docs = list(Path(tgt_path).open().readlines())
-        src, tgt = pack_examples(tok, src_docs, tgt_docs, max_tokens)
-        print(f"packed {split} split from {len(src_docs)} examples -> {len(src)}.")
-        Path(save_path / f"{split}.source").open("w").write("\n".join(src))
-        Path(save_path / f"{split}.target").open("w").write("\n".join(tgt))
+        src_docs = [x.rstrip() for x in Path(src_path).open().readlines()]
+        tgt_docs = [x.rstrip() for x in Path(tgt_path).open().readlines()]
+        packed_src, packed_tgt = pack_examples(tok, src_docs, tgt_docs, max_tokens)
+        print(f"packed {split} split from {len(src_docs)} examples -> {len(packed_src)}.")
+        Path(save_path / f"{split}.source").open("w").write("\n".join(packed_src))
+        Path(save_path / f"{split}.target").open("w").write("\n".join(packed_tgt))
 
 
 def packer_cli():

examples/seq2seq/test_seq2seq_examples.py

@@ -254,11 +254,19 @@ def test_finetune(model):
 
 def test_pack_dataset():
     tokenizer = AutoTokenizer.from_pretrained("facebook/mbart-large-cc25")
+
     tmp_dir = Path(make_test_data_dir())
+    orig_examples = tmp_dir.joinpath("train.source").open().readlines()
     save_dir = Path(tempfile.mkdtemp(prefix="packed_"))
     pack_data_dir(tokenizer, tmp_dir, 128, save_dir)
     orig_paths = {x.name for x in tmp_dir.iterdir()}
     new_paths = {x.name for x in save_dir.iterdir()}
+    packed_examples = save_dir.joinpath("train.source").open().readlines()
+    # orig: [' Sam ate lunch today.\n', 'Sams lunch ingredients.']
+    # desired_packed: [' Sam ate lunch today.\n Sams lunch ingredients.']
+    assert len(packed_examples) < len(orig_examples)
+    assert len(packed_examples) == 1
+    assert len(packed_examples[0]) == sum(len(x) for x in orig_examples)
     assert orig_paths == new_paths