Test first batch matches

Summary:

Test Plan:

bytelatent/data/iterators/test_arrow_iterator.py

@@ -28,6 +28,7 @@ def test_basic_arrow_file():
         row_num=0,
         arrow_batch_size=100,
         s3_profile=None,
+        file_format="arrow",
     )
     arrow_file = initial_state.build()
     start_state = arrow_file.get_state()
@@ -57,6 +58,7 @@ def test_basic_arrow_file():
         row_num=251,
         arrow_batch_size=100,
         s3_profile=None,
+        file_format="arrow",
     )
     arrow_file = resumed_state.build()
     for example in arrow_file.create_iter():
@@ -77,6 +79,7 @@ def test_basic_arrow_file():
         row_num=0,
         arrow_batch_size=100,
         s3_profile=None,
+        file_format="arrow",
     )
     arrow_file = rank_state.build()
     expected_ids = []

bytelatent/data/test_data.py

@@ -0,0 +1,46 @@
+import os
+import pickle
+import pytest
+from omegaconf import OmegaConf
+from bytelatent.args import TrainArgs
+from bytelatent.constants import BLT_DATA
+
+
+def get_test_config():
+    if "BLT_INTERNAL" in os.environ:
+        internal_dir = os.environ["BLT_INTERNAL"]
+    else:
+        internal_dir = "../internal-blt/configs"
+    test_config = os.path.join(internal_dir, "tests.yaml")
+    return test_config
+
+
+@pytest.mark.skipif(
+    not os.path.exists(get_test_config()),
+    reason="Skipping since internal config is missing",
+)
+def test_first_batch_matches():
+    test_config_path = get_test_config()
+    default_cfg = OmegaConf.create(TrainArgs().model_dump())
+    file_cfg = OmegaConf.load(test_config_path)
+    merged_cfg = OmegaConf.merge(default_cfg, file_cfg)
+    merged_cfg = OmegaConf.to_container(merged_cfg, resolve=True, throw_on_missing=True)
+    train_args = TrainArgs.model_validate(merged_cfg)
+    # MP doesn't work with async very well, but it doesn't change logic
+    train_args.data.load_async = False
+
+    # Test data created by pickling first batch in train loop then exiting
+    with open(os.path.join(BLT_DATA, "fixtures", "first_batch_0.pickle"), "rb") as f:
+        first_batch = pickle.load(f)
+
+    # Emulate 1 node, 8 gpu training
+    data_loader = train_args.data.build_from_rank(0, 8)
+    batch_iterator = data_loader.create_iter()
+    print("Getting first batch")
+    batch = next(batch_iterator)
+    assert (batch.x == first_batch.x).all()
+    assert (batch.y == first_batch.y).all()
+    assert (batch.mask == first_batch.mask).all()
+    assert (batch.patch_lengths == first_batch.patch_lengths).all()
+    assert batch.ngram_ids is None and first_batch.ngram_ids is None
+    assert batch.is_final == False and batch.is_final == False

bytelatent/test_entropy_model.py

@@ -25,6 +25,7 @@ def test_entropy_model():
         row_num=0,
         arrow_batch_size=100,
         s3_profile=None,
+        file_format="arrow",
     )
     arrow_file = initial_state.build()
     tokenizer_args = TokenizerArgs(