feat(streaming): multinode example, dataloading benchmark, distributed smoke test

- examples/scaling/train_streaming_multinode.py: Accelerate-based distributed/
  resumable streaming training (no DistributedSampler; rank/world_size auto-resolved),
  checkpoints the dataset stream state, and supports a --dummy pure-dataloading path
  with throughput logging. SLURM launcher in slurm/train_streaming_robocasa.sh.
- benchmarks/streaming/benchmark_streaming.py: dummy-consumer dataloading benchmark
  (single / sarm frame modes) emitting frames/s/node, p50/p95/p99 sample latency,
  first-batch latency, and VideoDecoderCache reuse stats as JSON + CSV. SLURM launcher
  + README documenting the source/node/mode matrix and manual bucket prewarming.
- VideoDecoderCache: add hit/miss/eviction counters and a stats() method so the
  benchmark can surface decoder thrash (no new cache, no eviction-policy change).
- tests/datasets/test_streaming_distributed.py: accelerate-launch smoke test asserting
  per-rank disjointness; skips (does not false-pass) when <2 processes spawn.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
This commit is contained in:
Pepijn
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# Streaming dataloading benchmark
Measures **dataloading only** (no model) for `StreamingLeRobotDataset`: parquet read + video decode +
delta windowing + shuffle. A dummy consumer pulls batches and moves them to the device, so the numbers
isolate the data pipeline. Use it to compare sources (Hub vs. storage bucket vs. prewarmed bucket),
frame modes, and node counts, and to catch p95/p99 video-decode regressions.
## Run
```bash
python benchmarks/streaming/benchmark_streaming.py \
--repo_id pepijn223/robocasa_pretrain_human300_v4 \
--mode sarm --batch_size 64 --num_workers 12 --num_batches 200 \
--source hub --out_dir benchmarks/streaming/results
```
Multinode (per-node throughput) goes through Accelerate under SLURM:
```bash
sbatch slurm/benchmark_streaming_robocasa.sh
```
## Matrix
| Axis | Values |
| ---------- | -------------------------------------------------------------------------------------------------------------------- |
| Source | `hub` (verify now), `bucket`, `warmed_bucket` (bucket + prewarming; with user's help later) |
| Baseline | current `main` `StreamingLeRobotDataset` on Hub streaming |
| Nodes | 1 and 2 (per-node throughput should be independent) |
| Frame mode | `single` (1 frame, all cameras; target ≥ 120 frames/s/node) · `sarm` (8 steps spaced 1s; target ≥ 320 frames/s/node) |
`--source` is a label only; the actual source is whatever `--repo_id` / `--root` point at.
## Metrics emitted (JSON + CSV)
`frames_per_s_node`, `samples_per_s`, `first_batch_latency_s`, `p50/p95/p99_sample_latency_ms`,
`wallclock_s`, and `video_decoder_cache` (`hits`, `misses`, `evictions`, `hit_rate`, `size`). A low
cache `hit_rate` with high `p99` is the decoder-thrash signature — raise `--video_decoder_cache_size`
or `--buffer_size`, or reduce `num_workers`.
## Bucket sources & prewarming (manual)
Prewarming is a **server-side** Hugging Face storage-bucket feature — there is no client script. To
benchmark the `warmed_bucket` source:
1. Attach a storage bucket to the dataset and enable it (see
<https://huggingface.co/docs/hub/storage-buckets>). Buckets resolve through `fsspec`, the same as
`hf://`, so no code change is needed — point `--repo_id`/`--revision` (or `--root`) at the bucket.
2. Enable **prewarming** in the bucket settings and wait for warm-up to complete.
3. Run the benchmark with `--source warmed_bucket`. Compare against the cold `--source bucket` and the
`--source hub` baseline.
Manual only — not run in CI.
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# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""Dataloading-only benchmark for StreamingLeRobotDataset.
A dummy consumer pulls batches and moves them to the device; no model runs, so the numbers isolate the
data pipeline (parquet read + video decode + delta windowing + shuffle). Reports per-node throughput and
sample-latency percentiles, plus video-decoder-cache reuse stats, and emits JSON + CSV.
Frame modes (matching the streaming design targets):
- ``single``: one frame, all cameras (target >= 120 frames/s/node).
- ``sarm``: an 8-step window spaced 1s (delta over 8s) (target >= 320 frames/s/node).
Example (stream from the Hub, single node):
python benchmarks/streaming/benchmark_streaming.py \
--repo_id pepijn223/robocasa_pretrain_human300_v4 --mode sarm \
--batch_size 64 --num_workers 12 --num_batches 200 --out_dir benchmarks/streaming/results
Distributed / multinode runs go through Accelerate; see ``slurm/benchmark_streaming_robocasa.sh``. Set
``--source`` purely for labeling the output (``hub`` / ``bucket`` / ``warmed_bucket``); the actual source
is whatever ``--repo_id``/``--root`` point at. See the README for bucket prewarming.
"""
import argparse
import csv
import json
import statistics
import time
from pathlib import Path
import torch
from torch.utils.data import DataLoader
from lerobot.datasets import LeRobotDatasetMetadata, StreamingLeRobotDataset
from lerobot.utils.constants import ACTION
def parse_args() -> argparse.Namespace:
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument("--repo_id", type=str, required=True)
parser.add_argument("--root", type=str, default=None, help="Local/prewarmed root (else stream from Hub).")
parser.add_argument("--mode", choices=["single", "sarm"], default="single")
parser.add_argument("--source", type=str, default="hub", help="Label only: hub | bucket | warmed_bucket.")
parser.add_argument("--batch_size", type=int, default=64)
parser.add_argument("--num_workers", type=int, default=8)
parser.add_argument("--buffer_size", type=int, default=2000)
parser.add_argument("--video_decoder_cache_size", type=int, default=None)
parser.add_argument("--num_batches", type=int, default=200)
parser.add_argument("--warmup_batches", type=int, default=5, help="Excluded from steady-state stats.")
parser.add_argument("--device", type=str, default="cuda" if torch.cuda.is_available() else "cpu")
parser.add_argument("--out_dir", type=str, default="benchmarks/streaming/results")
return parser.parse_args()
def build_dataset(args: argparse.Namespace, meta: LeRobotDatasetMetadata) -> StreamingLeRobotDataset:
# sarm: an 8-step window spaced 1s => an 8s delta window (the SARM stress case).
delta_timestamps = {ACTION: [float(t) for t in range(8)]} if args.mode == "sarm" else None
return StreamingLeRobotDataset(
args.repo_id,
root=args.root,
delta_timestamps=delta_timestamps,
buffer_size=args.buffer_size,
video_decoder_cache_size=args.video_decoder_cache_size,
tolerance_s=1e-3,
)
def percentile(values: list[float], pct: float) -> float:
if not values:
return float("nan")
ordered = sorted(values)
k = max(0, min(len(ordered) - 1, int(round((pct / 100.0) * (len(ordered) - 1)))))
return ordered[k]
def main() -> None:
args = parse_args()
device = torch.device(args.device)
meta = LeRobotDatasetMetadata(args.repo_id, root=args.root)
dataset = build_dataset(args, meta)
loader = DataLoader(
dataset,
batch_size=args.batch_size,
num_workers=args.num_workers,
pin_memory=device.type == "cuda",
drop_last=True,
prefetch_factor=2 if args.num_workers > 0 else None,
)
sample_latencies_ms: list[float] = []
frames = 0
first_batch_latency_s = None
t_start = time.perf_counter()
t_prev = t_start
for i, batch in enumerate(loader):
# Dummy consume: move tensors to the device, mimicking what a real trainer would do.
for value in batch.values():
if torch.is_tensor(value):
value.to(device, non_blocking=device.type == "cuda")
now = time.perf_counter()
if first_batch_latency_s is None:
first_batch_latency_s = now - t_start
if i >= args.warmup_batches:
per_sample_ms = (now - t_prev) / args.batch_size * 1000.0
sample_latencies_ms.append(per_sample_ms)
frames += args.batch_size
t_prev = now
if i + 1 >= args.num_batches:
break
elapsed = time.perf_counter() - t_start
steady_elapsed_s = sum(sample_latencies_ms) / 1000.0
cache_stats = dataset.video_decoder_cache.stats() if dataset.video_decoder_cache is not None else {}
results = {
"repo_id": args.repo_id,
"source": args.source,
"mode": args.mode,
"batch_size": args.batch_size,
"num_workers": args.num_workers,
"buffer_size": args.buffer_size,
"num_cameras": len(meta.video_keys),
"fps": meta.fps,
"device": str(device),
"frames_measured": frames,
"first_batch_latency_s": round(first_batch_latency_s or float("nan"), 4),
"frames_per_s_node": round(frames / steady_elapsed_s, 2) if steady_elapsed_s else 0.0,
"samples_per_s": round(frames / steady_elapsed_s, 2) if steady_elapsed_s else 0.0,
"p50_sample_latency_ms": round(statistics.median(sample_latencies_ms), 3)
if sample_latencies_ms
else None,
"p95_sample_latency_ms": round(percentile(sample_latencies_ms, 95), 3),
"p99_sample_latency_ms": round(percentile(sample_latencies_ms, 99), 3),
"wallclock_s": round(elapsed, 2),
"video_decoder_cache": cache_stats,
}
out_dir = Path(args.out_dir)
out_dir.mkdir(parents=True, exist_ok=True)
tag = f"{args.source}_{args.mode}_bs{args.batch_size}_w{args.num_workers}"
(out_dir / f"{tag}.json").write_text(json.dumps(results, indent=2))
flat = {k: (json.dumps(v) if isinstance(v, dict) else v) for k, v in results.items()}
with open(out_dir / f"{tag}.csv", "w", newline="") as f:
writer = csv.DictWriter(f, fieldnames=list(flat))
writer.writeheader()
writer.writerow(flat)
print("Command config:", vars(args))
print(json.dumps(results, indent=2))
print(f"Wrote {out_dir / tag}.json and .csv")
if __name__ == "__main__":
main()