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from __future__ import annotations
import argparse
from pathlib import Path
import torch
from torch.optim import AdamW
from tqdm import tqdm
from transformers import AutoModelForCausalLM, AutoTokenizer
from .common import (
cosine_schedule,
dtype_for_device,
parameter_count,
read_json,
seed_everything,
)
from .io import load_feature_pair, select_rows
from .models import PrefixAdapter
def parse_args() -> argparse.Namespace:
p = argparse.ArgumentParser()
p.add_argument("--manifest", default="artifacts/manifest.json")
p.add_argument("--vision", default="artifacts/vision.pt")
p.add_argument("--text", default="artifacts/text.pt")
p.add_argument("--output", default="artifacts/prefix.pt")
p.add_argument("--device", default="cuda:1")
p.add_argument("--steps", type=int, default=3_000)
p.add_argument("--batch-size", type=int, default=32)
p.add_argument("--prefix-length", type=int, default=8)
p.add_argument("--hidden-dim", type=int, default=2048)
p.add_argument("--max-length", type=int, default=48)
p.add_argument("--lr", type=float, default=3e-4)
p.add_argument("--warmup", type=int, default=200)
p.add_argument("--seed", type=int, default=20260728)
return p.parse_args()
def main() -> None:
args = parse_args()
seed_everything(args.seed)
manifest = read_json(args.manifest)
_, text, _, tlookup = load_feature_pair(args.vision, args.text)
train_rows = manifest["text_only_train"]
semantic = select_rows(text["features"], tlookup, train_rows)
captions_by_row = {
int(row): caption for row, caption in zip(text["rows"], text["captions"])
}
captions = [captions_by_row[int(row)] for row in train_rows]
tokenizer = AutoTokenizer.from_pretrained(text["model"])
if tokenizer.pad_token_id is None:
tokenizer.pad_token = tokenizer.eos_token
tokenizer.padding_side = "right"
dtype = dtype_for_device(args.device)
lm = AutoModelForCausalLM.from_pretrained(
text["model"], torch_dtype=dtype
).to(args.device)
lm.eval()
for parameter in lm.parameters():
parameter.requires_grad_(False)
lm_dim = lm.get_input_embeddings().embedding_dim
adapter = PrefixAdapter(
semantic_dim=semantic.shape[-1],
lm_dim=lm_dim,
prefix_length=args.prefix_length,
hidden_dim=args.hidden_dim,
).to(args.device)
print(f"Prefix adapter parameters: {parameter_count(adapter):,}")
optimizer = AdamW(adapter.parameters(), lr=args.lr, weight_decay=1e-4)
generator = torch.Generator().manual_seed(args.seed)
history = []
progress = tqdm(range(args.steps), desc="text-only prefix")
for step in progress:
ids = torch.randint(
len(semantic), (args.batch_size,), generator=generator
)
batch_captions = [captions[int(i)] for i in ids]
tokens = tokenizer(
batch_captions,
padding=True,
truncation=True,
max_length=args.max_length,
return_tensors="pt",
)
input_ids = tokens["input_ids"].to(args.device)
attention = tokens["attention_mask"].to(args.device)
prefix = adapter(semantic[ids].to(args.device)).to(dtype)
token_embeddings = lm.get_input_embeddings()(input_ids)
inputs_embeds = torch.cat([prefix, token_embeddings], dim=1)
prefix_attention = torch.ones(
prefix.shape[:2], dtype=attention.dtype, device=args.device
)
full_attention = torch.cat([prefix_attention, attention], dim=1)
labels = input_ids.clone()
labels[attention == 0] = -100
prefix_labels = torch.full(
prefix.shape[:2], -100, dtype=labels.dtype, device=args.device
)
full_labels = torch.cat([prefix_labels, labels], dim=1)
result = lm(
inputs_embeds=inputs_embeds,
attention_mask=full_attention,
labels=full_labels,
use_cache=False,
return_dict=True,
)
loss = result.loss
optimizer.zero_grad(set_to_none=True)
loss.backward()
torch.nn.utils.clip_grad_norm_(adapter.parameters(), 1.0)
optimizer.step()
scale = cosine_schedule(step, args.steps, args.warmup)
for group in optimizer.param_groups:
group["lr"] = args.lr * scale
if step % 20 == 0:
progress.set_postfix(loss=f"{loss.item():.3f}")
if step % 100 == 0 or step == args.steps - 1:
history.append({"step": step, "loss": float(loss.item())})
state = {
"config": adapter.config(),
"state_dict": adapter.state_dict(),
"text_model": text["model"],
"text_layer": text["layer"],
"args": vars(args),
"history": history,
"training": "text only; no image features or image-text pairs",
}
Path(args.output).parent.mkdir(parents=True, exist_ok=True)
torch.save(state, args.output)
print(f"Wrote {args.output}")
if __name__ == "__main__":
main()
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