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lerobot/scripts/bench_episode_byte_cache.py
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#!/usr/bin/env python
# Copyright 2026 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
from __future__ import annotations
import argparse
import random
import resource
import tempfile
import threading
import time
from collections.abc import Sequence
from concurrent.futures import ThreadPoolExecutor
from dataclasses import dataclass
from pathlib import Path
import fsspec
import numpy as np
import pyarrow as pa
import pyarrow.compute as pc
import pyarrow.parquet as pq
from lerobot.datasets.dataset_metadata import LeRobotDatasetMetadata
from lerobot.datasets.episode_video_streaming import (
EpisodeByteCache,
EpisodeVideoManifest,
NativeHTTPRangeFetcher,
assert_hf_hub_range_cache_branch,
make_range_fetcher,
)
from lerobot.datasets.video_utils import VideoDecoderCache, decode_video_frames_torchcodec
DEFAULT_REPO = "allenai/MolmoAct2-BimanualYAM-Dataset"
DEFAULT_REVISION = "e9f21ae15074330839f2ac25ed4b49d76dfa1f9c"
DEFAULT_DATA_ROOT = "hf://buckets/pepijn223/MolmoAct2-BimanualYAM-Dataset-bucket"
SIDECAR_CACHE_DIR = Path(tempfile.gettempdir()) / "lerobot-sidecars"
FULL_SIDECAR_NAME = "molmoact2-full.npz"
def parse_args() -> argparse.Namespace:
parser = argparse.ArgumentParser(description="Benchmark episode-level streaming mini-MP4 cache.")
parser.add_argument("--repo-id", default=DEFAULT_REPO)
parser.add_argument("--revision", default=DEFAULT_REVISION)
parser.add_argument("--data-root", default=DEFAULT_DATA_ROOT)
parser.add_argument(
"--strategy",
choices=("both", "full", "indexed", "remote-decoder", "native-http", "random-frames"),
default="both",
help=argparse.SUPPRESS,
)
parser.add_argument("--num-episodes", type=int, default=512)
parser.add_argument(
"--manifest-episodes",
type=int,
default=None,
help="Limit manifest construction to the first N episodes for local smoke tests.",
)
parser.add_argument("--pool-size", type=int, default=16)
parser.add_argument(
"--frame-pool-size",
type=int,
default=4096,
help="Number of random frame/camera targets for --strategy random-frames.",
)
parser.add_argument(
"--coalesce-gap-kb",
type=int,
default=256,
help="Merge random-frame byte windows separated by at most this many KiB.",
)
parser.add_argument(
"--random-frame-backend",
choices=("fsspec", "native-http"),
default="native-http",
help="Range backend for --strategy random-frames.",
)
parser.add_argument("--workers", type=int, default=8)
parser.add_argument(
"--include-decode",
action="store_true",
help="Also run decoder-opening/frame-decode comparison tracks. Fetch-only is the default.",
)
parser.add_argument("--decode-workers", type=int, default=1)
parser.add_argument("--prefetch-ahead", type=int, default=8)
parser.add_argument("--frames-per-episode", type=int, default=16)
parser.add_argument("--max-probe-mb", type=int, default=64)
parser.add_argument("--seed", type=int, default=0)
parser.add_argument("--byte-budget-gb", type=float, default=80)
parser.add_argument(
"--in-memory", action="store_true", help="Accepted for compatibility; manifest is always in memory."
)
parser.add_argument("--no-hub-branch-assert", action="store_true")
return parser.parse_args()
def _episode_pool(total: int, requested: int, pool_size: int, seed: int) -> list[int]:
rng = random.Random(seed)
upper = min(total, requested)
if pool_size > upper:
raise ValueError(f"pool-size={pool_size} exceeds available episodes={upper}")
return rng.sample(range(upper), pool_size)
def _timestamps(manifest: EpisodeVideoManifest, episodes: Sequence[int], frames_per_episode: int, seed: int):
rng = random.Random(seed)
out: dict[tuple[int, str], list[float]] = {}
for ep in episodes:
for camera_key in manifest.video_keys:
span = manifest.lookup(ep, camera_key)
lo = span.first_pts
hi = max(span.last_pts, lo)
out[(ep, camera_key)] = sorted(rng.uniform(lo, hi) for _ in range(frames_per_episode))
return out
def _timestamps_from_meta(
meta: LeRobotDatasetMetadata, episodes: Sequence[int], frames_per_episode: int, seed: int
) -> dict[tuple[int, str], list[float]]:
rng = random.Random(seed)
out: dict[tuple[int, str], list[float]] = {}
for ep in episodes:
row = meta.episodes[ep]
for camera_key in meta.video_keys:
lo = float(row[f"videos/{camera_key}/from_timestamp"])
hi = max(float(row[f"videos/{camera_key}/to_timestamp"]), lo)
out[(ep, camera_key)] = sorted(rng.uniform(lo, hi) for _ in range(frames_per_episode))
return out
def _bytes_for(manifest: EpisodeVideoManifest, episodes: Sequence[int]) -> int:
total = 0
for ep in episodes:
for camera_key in manifest.video_keys:
total += manifest.lookup(ep, camera_key).mdat_length
return total
@dataclass(frozen=True)
class FrameByteWindow:
file_id: int
file_path: str
byte_offset: int
byte_length: int
useful_bytes: int
sample_lo: int
sample_hi: int
target_sample: int
@dataclass(frozen=True)
class CoalescedByteRange:
file_id: int
file_path: str
byte_offset: int
byte_length: int
windows: int
useful_bytes: int
def _previous_sync_sample(sync_samples: np.ndarray, target_sample: int) -> int:
prev = sync_samples[sync_samples <= target_sample]
if len(prev):
return int(prev[-1])
if len(sync_samples):
return int(sync_samples[0])
return target_sample
def _frame_window_for_sample(
manifest: EpisodeVideoManifest, episode_index: int, camera_key: str, ts: float
) -> FrameByteWindow:
span = manifest.lookup(episode_index, camera_key)
file_record = manifest.file_lookup(span.file_id)
mp4 = file_record.mp4
if len(mp4.sample_pts) == 0:
raise ValueError(f"{file_record.file_path} has no indexed samples")
target = int(np.searchsorted(mp4.sample_pts, ts, side="left"))
target = min(max(target, 0), len(mp4.sample_pts) - 1)
lo = _previous_sync_sample(mp4.sync_samples, target)
hi = max(target, lo)
offsets = mp4.sample_offsets[lo : hi + 1]
sizes = mp4.sample_sizes[lo : hi + 1]
byte_offset = int(offsets.min())
byte_end = int((offsets + sizes).max())
return FrameByteWindow(
file_id=span.file_id,
file_path=file_record.file_path,
byte_offset=byte_offset,
byte_length=byte_end - byte_offset,
useful_bytes=int(sizes.sum()),
sample_lo=lo,
sample_hi=hi,
target_sample=target,
)
def _sample_frame_windows(
manifest: EpisodeVideoManifest,
*,
benchmark_episode_count: int,
frame_pool_size: int,
seed: int,
) -> list[FrameByteWindow]:
rng = random.Random(seed)
windows = []
for _ in range(frame_pool_size):
ep = rng.randrange(benchmark_episode_count)
camera_key = rng.choice(manifest.video_keys)
span = manifest.lookup(ep, camera_key)
ts = rng.uniform(span.first_pts, max(span.last_pts, span.first_pts))
windows.append(_frame_window_for_sample(manifest, ep, camera_key, ts))
return windows
def _coalesce_windows(windows: Sequence[FrameByteWindow], gap_bytes: int) -> list[CoalescedByteRange]:
by_file: dict[int, list[FrameByteWindow]] = {}
for window in windows:
by_file.setdefault(window.file_id, []).append(window)
ranges = []
for file_id, file_windows in by_file.items():
ordered = sorted(file_windows, key=lambda w: w.byte_offset)
current_start = ordered[0].byte_offset
current_end = ordered[0].byte_offset + ordered[0].byte_length
current_path = ordered[0].file_path
current_windows = 1
current_useful_bytes = ordered[0].useful_bytes
for window in ordered[1:]:
start = window.byte_offset
end = window.byte_offset + window.byte_length
if start <= current_end + gap_bytes:
current_end = max(current_end, end)
current_windows += 1
current_useful_bytes += window.useful_bytes
continue
ranges.append(
CoalescedByteRange(
file_id=file_id,
file_path=current_path,
byte_offset=current_start,
byte_length=current_end - current_start,
windows=current_windows,
useful_bytes=current_useful_bytes,
)
)
current_start = start
current_end = end
current_path = window.file_path
current_windows = 1
current_useful_bytes = window.useful_bytes
ranges.append(
CoalescedByteRange(
file_id=file_id,
file_path=current_path,
byte_offset=current_start,
byte_length=current_end - current_start,
windows=current_windows,
useful_bytes=current_useful_bytes,
)
)
return ranges
def _decode_all(
cache: EpisodeByteCache, timestamps: dict[tuple[int, str], list[float]], *, decode_workers: int
) -> float:
start = time.perf_counter()
items = list(timestamps.items())
if decode_workers <= 1:
for (ep, camera_key), ts in items:
cache.get_frames(ep, camera_key, ts)
else:
with ThreadPoolExecutor(max_workers=decode_workers) as pool:
futures = [pool.submit(cache.get_frames, ep, camera_key, ts) for (ep, camera_key), ts in items]
for future in futures:
future.result()
return time.perf_counter() - start
def _fill_cache(cache: EpisodeByteCache, episodes: Sequence[int]) -> float:
start = time.perf_counter()
for ep in episodes:
cache.submit_prefetch(ep)
for ep in episodes:
cache.ensure_ready(ep)
return time.perf_counter() - start
def _samples_per_s(elapsed_s: float, episodes: Sequence[int], frames_per_episode: int) -> float:
if elapsed_s <= 0:
return float("inf")
return len(episodes) * frames_per_episode / elapsed_s
def _log(message: str) -> None:
print(message, flush=True)
def _format_duration(seconds: float) -> str:
if seconds < 60:
return f"{seconds:.1f}s"
if seconds < 3600:
return f"{seconds / 60:.1f}m"
return f"{seconds / 3600:.1f}h"
def _current_rss_mib() -> float | None:
status_path = Path("/proc/self/status")
if not status_path.exists():
return None
for line in status_path.read_text().splitlines():
if line.startswith("VmRSS:"):
return float(line.split()[1]) / 1024
return None
def _peak_rss_mib() -> float:
rss = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
# Linux reports KiB; macOS reports bytes.
if rss > 10**8:
return rss / 1024**2
return rss / 1024
def _memory_snapshot() -> dict[str, float | None]:
return {"rss_mib": _current_rss_mib(), "peak_rss_mib": _peak_rss_mib()}
def _print_memory_summary(start: dict[str, float | None], end: dict[str, float | None]) -> None:
start_rss = start["rss_mib"]
end_rss = end["rss_mib"]
delta = None if start_rss is None or end_rss is None else end_rss - start_rss
print()
print("| Memory | MiB |")
print("|---|---:|")
if start_rss is not None:
print(f"| rss start | {start_rss:.1f} |")
if end_rss is not None:
print(f"| rss end | {end_rss:.1f} |")
if delta is not None:
print(f"| rss delta | {delta:.1f} |")
print(f"| peak rss | {end['peak_rss_mib']:.1f} |")
def _root_join(data_root: str, relative_path: str) -> str:
if data_root.startswith("hf://"):
return f"{data_root.rstrip('/')}/{relative_path}"
return str(Path(data_root) / relative_path)
def _find_or_download_sidecar(data_root: str, manifest_episode_count: int) -> Path | None:
_ = manifest_episode_count
local = SIDECAR_CACHE_DIR / FULL_SIDECAR_NAME
if _valid_sidecar(local):
return local
if local.exists():
print(f"mp4_sidecar_invalid_local: {local}")
local.unlink()
remote_relative = f"meta/mp4-sidecars/{FULL_SIDECAR_NAME}"
remote = _root_join(data_root, remote_relative)
protocol = "hf" if data_root.startswith("hf://") else "file"
fs = fsspec.filesystem(protocol)
if not fs.exists(remote):
return None
local.parent.mkdir(parents=True, exist_ok=True)
print(f"downloading_mp4_sidecar: {remote} -> {local}")
if data_root.startswith("hf://"):
_download_sidecar_native_http(data_root, remote_relative, local)
else:
fs.get(remote, str(local))
return local
def _valid_sidecar(path: Path) -> bool:
if not path.exists():
return False
try:
with np.load(path, allow_pickle=False) as data:
return "manifest_json" in data
except Exception:
return False
def _download_sidecar_native_http(data_root: str, relative_path: str, local: Path) -> None:
fetcher = NativeHTTPRangeFetcher(data_root, max_connections=16)
tmp = local.with_suffix(local.suffix + ".tmp")
try:
size = fetcher.info_size(relative_path)
chunk_size = 16 * 1024 * 1024
ranges = [(offset, min(chunk_size, size - offset)) for offset in range(0, size, chunk_size)]
with tmp.open("wb") as out_file:
out_file.truncate(size)
def read_chunk(offset_length: tuple[int, int]) -> tuple[int, bytes]:
offset, length = offset_length
return offset, fetcher.read_range(relative_path, offset, length)
start = time.perf_counter()
done = 0
with ThreadPoolExecutor(max_workers=8) as pool:
futures = [pool.submit(read_chunk, item) for item in ranges]
with tmp.open("r+b") as rw_file:
for future in futures:
offset, data = future.result()
rw_file.seek(offset)
rw_file.write(data)
done += len(data)
elapsed = max(time.perf_counter() - start, 1e-9)
print(
f"sidecar_download: {done / 1024**2:.1f}/{size / 1024**2:.1f} MiB "
f"({done / elapsed / 1024**2:.1f} MiB/s)",
flush=True,
)
tmp.replace(local)
finally:
fetcher.close()
class EpisodeParquetReader:
def __init__(self, meta: LeRobotDatasetMetadata, data_root: str):
self.meta = meta
self.data_root = data_root
protocol = "hf" if data_root.startswith("hf://") else "file"
self.fs = fsspec.filesystem(protocol)
self._episode_row_groups = self._build_episode_row_groups()
self._table_cache: dict[str, pa.Table] = {}
self._cache_lock = threading.Lock()
def read_episode(self, episode_index: int) -> None:
relative_path = str(self.meta.get_data_file_path(episode_index))
table = self._read_table(relative_path)
table.filter(pc.equal(table["episode_index"], episode_index))
def _read_table(self, relative_path: str) -> pa.Table:
with self._cache_lock:
table = self._table_cache.get(relative_path)
if table is not None:
return table
with self.fs.open(
_root_join(self.data_root, relative_path), "rb", block_size=2**20, cache_type="none"
) as f:
table = pq.ParquetFile(f).read()
with self._cache_lock:
return self._table_cache.setdefault(relative_path, table)
def submit_read_episode(self, pool: ThreadPoolExecutor, episode_index: int):
return pool.submit(self.read_episode, episode_index)
def read_episodes(self, episodes: Sequence[int], *, workers: int) -> float:
start = time.perf_counter()
if workers <= 1:
for ep in episodes:
self.read_episode(ep)
else:
with ThreadPoolExecutor(max_workers=workers) as pool:
futures = [pool.submit(self.read_episode, ep) for ep in episodes]
for future in futures:
future.result()
return time.perf_counter() - start
def _build_episode_row_groups(self) -> dict[int, int]:
counts: dict[tuple[int, int], int] = {}
row_groups = {}
for ep_idx in range(int(self.meta.total_episodes)):
ep = self.meta.episodes[ep_idx]
key = (int(ep["data/chunk_index"]), int(ep["data/file_index"]))
row_groups[ep_idx] = counts.get(key, 0)
counts[key] = row_groups[ep_idx] + 1
return row_groups
def run_fetch_pool(
manifest: EpisodeVideoManifest,
data_root: str,
episodes: Sequence[int],
byte_budget: int,
workers: int,
range_backend: str,
) -> dict[str, float]:
with EpisodeByteCache(
manifest,
data_root,
byte_budget=byte_budget,
workers=workers,
range_backend=range_backend,
open_decoders=False,
) as cache:
elapsed = _fill_cache(cache, episodes)
timings = cache.timing_summary()
byte_count = _bytes_for(manifest, episodes)
episode_mb = byte_count / len(episodes) / 1024**2
job_count = max(timings["jobs"], 1.0)
return {
"fetch_s": elapsed,
"fetch_mbps": byte_count / elapsed / 1024**2,
"fetch_episodes_s": len(episodes) / elapsed,
"episode_mb": episode_mb,
"avg_mb_miss": byte_count / (len(episodes) * len(manifest.video_keys)) / 1024**2,
"jobs": timings["jobs"],
"lookup_ms": timings["lookup_s"] * 1000 / job_count,
"range_fetch_ms": timings["fetch_s"] * 1000 / job_count,
"synthesize_ms": timings["synthesize_s"] * 1000 / job_count,
"store_ms": timings["store_s"] * 1000 / job_count,
}
def run_parallel(
manifest: EpisodeVideoManifest,
data_root: str,
episodes: Sequence[int],
timestamps: dict[tuple[int, str], list[float]],
byte_budget: int,
workers: int,
decode_workers: int,
frames_per_episode: int,
parquet_reader: EpisodeParquetReader,
range_backend: str,
) -> dict[str, float]:
with EpisodeByteCache(
manifest,
data_root,
byte_budget=byte_budget,
workers=workers,
range_backend=range_backend,
open_decoders=False,
) as cache:
parquet_s = parquet_reader.read_episodes(episodes, workers=workers)
fetch_s = _fill_cache(cache, episodes)
decoder_start = time.perf_counter()
for ep in episodes:
for camera_key in manifest.video_keys:
cache.get_decoder(ep, camera_key)
decoder_s = time.perf_counter() - decoder_start
decode_s = _decode_all(cache, timestamps, decode_workers=decode_workers)
byte_count = _bytes_for(manifest, episodes)
return {
"fetch_s": fetch_s,
"fetch_mbps": byte_count / fetch_s / 1024**2,
"fetch_episodes_s": len(episodes) / fetch_s,
"parquet_s": parquet_s,
"decoder_ms_miss": decoder_s * 1000 / (len(episodes) * len(manifest.video_keys)),
"decode_samples_s": _samples_per_s(decode_s, episodes, frames_per_episode),
}
def run_overlapped(
manifest: EpisodeVideoManifest,
data_root: str,
episodes: Sequence[int],
timestamps: dict[tuple[int, str], list[float]],
byte_budget: int,
workers: int,
decode_workers: int,
frames_per_episode: int,
prefetch_ahead: int,
parquet_reader: EpisodeParquetReader,
range_backend: str,
) -> dict[str, float]:
with EpisodeByteCache(
manifest,
data_root,
byte_budget=byte_budget,
workers=workers,
range_backend=range_backend,
open_decoders=True,
) as cache:
start = time.perf_counter()
video_wait_decode_s = 0.0
parquet_wait_s = 0.0
parquet_pool = ThreadPoolExecutor(max_workers=max(1, min(workers, len(episodes))))
parquet_futures = {
ep: parquet_reader.submit_read_episode(parquet_pool, ep) for ep in episodes[:prefetch_ahead]
}
for ep in episodes[:prefetch_ahead]:
cache.submit_prefetch(ep)
try:
for idx, ep in enumerate(episodes):
next_idx = idx + prefetch_ahead
if next_idx < len(episodes):
next_ep = episodes[next_idx]
cache.submit_prefetch(next_ep)
parquet_futures[next_ep] = parquet_reader.submit_read_episode(parquet_pool, next_ep)
parquet_start = time.perf_counter()
parquet_futures.pop(ep).result()
parquet_wait_s += time.perf_counter() - parquet_start
video_start = time.perf_counter()
cache.ensure_ready(ep)
if decode_workers <= 1:
for camera_key in manifest.video_keys:
cache.get_frames(ep, camera_key, timestamps[(ep, camera_key)])
else:
with ThreadPoolExecutor(max_workers=decode_workers) as pool:
futures = [
pool.submit(cache.get_frames, ep, camera_key, timestamps[(ep, camera_key)])
for camera_key in manifest.video_keys
]
for future in futures:
future.result()
video_wait_decode_s += time.perf_counter() - video_start
finally:
parquet_pool.shutdown(wait=True)
elapsed = time.perf_counter() - start
return {
"samples_s": _samples_per_s(elapsed, episodes, frames_per_episode),
"video_samples_s": _samples_per_s(video_wait_decode_s, episodes, frames_per_episode),
"parquet_samples_s": _samples_per_s(parquet_wait_s, episodes, frames_per_episode),
"wall_s": elapsed,
"video_wait_decode_s": video_wait_decode_s,
"parquet_wait_s": parquet_wait_s,
}
_remote_decoder_local = threading.local()
def _remote_decoder_cache() -> VideoDecoderCache:
cache = getattr(_remote_decoder_local, "cache", None)
if cache is None:
cache = VideoDecoderCache(max_size=None)
_remote_decoder_local.cache = cache
return cache
def _decode_remote_source(
meta: LeRobotDatasetMetadata,
data_root: str,
episode_index: int,
camera_key: str,
timestamps: list[float],
):
video_path = _root_join(data_root, str(meta.get_video_file_path(episode_index, camera_key)))
return decode_video_frames_torchcodec(
video_path,
timestamps,
tolerance_s=1.0 / float(meta.fps),
decoder_cache=_remote_decoder_cache(),
return_uint8=True,
)
def run_remote_decoder(
meta: LeRobotDatasetMetadata,
data_root: str,
episodes: Sequence[int],
timestamps: dict[tuple[int, str], list[float]],
*,
frames_per_episode: int,
decode_workers: int,
parquet_reader: EpisodeParquetReader,
) -> dict[str, float]:
items = [
(ep, camera_key, timestamps[(ep, camera_key)]) for ep in episodes for camera_key in meta.video_keys
]
start = time.perf_counter()
for ep, camera_key, ts in items:
if camera_key == meta.video_keys[0]:
parquet_reader.read_episode(ep)
_decode_remote_source(meta, data_root, ep, camera_key, ts)
sequential_s = time.perf_counter() - start
start = time.perf_counter()
if decode_workers <= 1:
for ep, camera_key, ts in items:
if camera_key == meta.video_keys[0]:
parquet_reader.read_episode(ep)
_decode_remote_source(meta, data_root, ep, camera_key, ts)
else:
with ThreadPoolExecutor(max_workers=decode_workers) as pool:
parquet_futures = [pool.submit(parquet_reader.read_episode, ep) for ep in episodes]
futures = [
pool.submit(_decode_remote_source, meta, data_root, ep, camera_key, ts)
for ep, camera_key, ts in items
]
for future in parquet_futures:
future.result()
for future in futures:
future.result()
parallel_s = time.perf_counter() - start
return {
"sequential_samples_s": _samples_per_s(sequential_s, episodes, frames_per_episode),
"parallel_samples_s": _samples_per_s(parallel_s, episodes, frames_per_episode),
}
def run_indexed_strategy(
meta: LeRobotDatasetMetadata,
data_root: str,
args: argparse.Namespace,
parquet_reader: EpisodeParquetReader,
*,
range_backend: str = "fsspec",
label: str = "indexed",
sidecar_path: str | None = None,
) -> None:
_log(f"starting_strategy: {label}")
memory_start = _memory_snapshot()
manifest_start = time.perf_counter()
dataset_episode_count = int(meta.total_episodes)
manifest_episode_count = args.manifest_episodes or dataset_episode_count
manifest_episode_count = min(manifest_episode_count, dataset_episode_count, args.num_episodes)
manifest = EpisodeVideoManifest.build(
meta,
data_root,
episode_indices=range(manifest_episode_count),
range_backend=range_backend,
workers=args.workers,
max_probe_bytes=args.max_probe_mb * 1024 * 1024,
sidecar_path=sidecar_path,
)
manifest_s = time.perf_counter() - manifest_start
_log(f"{label}: manifest_build_s={manifest_s:.2f}")
benchmark_episode_count = min(dataset_episode_count, args.num_episodes)
episodes = _episode_pool(dataset_episode_count, args.num_episodes, args.pool_size, args.seed)
byte_budget = int(args.byte_budget_gb * 1024**3)
byte_count = _bytes_for(manifest, episodes)
_log(
f"{label}: planned_video_fetch={byte_count / 1024**3:.2f} GiB per fetch track "
f"({byte_count / len(episodes) / 1024**2:.1f} MiB/episode)"
)
_log(f"{label}: filling episode byte cache with {args.workers} workers")
fetch_pool = run_fetch_pool(manifest, data_root, episodes, byte_budget, args.workers, range_backend)
estimated_dataset_s = dataset_episode_count / fetch_pool["fetch_episodes_s"]
estimated_benchmark_s = benchmark_episode_count / fetch_pool["fetch_episodes_s"]
print(f"manifest_build_s: {manifest_s:.2f}")
print(f"strategy: {label}")
print(f"range_backend: {range_backend}")
print(f"mp4_sidecar: {sidecar_path or 'none'}")
print(f"data_root: {data_root}")
print(f"dataset_episodes: {dataset_episode_count}")
print(f"benchmark_episodes: {benchmark_episode_count}")
print(f"pool_episodes: {len(episodes)}")
print(f"sampled_episodes: {episodes}")
print(f"cameras: {manifest.video_keys}")
print()
print(
"| Track | fetch MB/s | fetch eps/s | wall s | est benchmark | est full dataset | avg MB/camera | notes |"
)
print("|---|---:|---:|---:|---:|---:|---:|---|")
print(
f"| EPISODE POOL FETCH | {fetch_pool['fetch_mbps']:.1f} | "
f"{fetch_pool['fetch_episodes_s']:.2f} | {fetch_pool['fetch_s']:.2f} | "
f"{_format_duration(estimated_benchmark_s)} | {_format_duration(estimated_dataset_s)} | "
f"{fetch_pool['avg_mb_miss']:.1f} | {args.workers} workers, no decoder open/frame decode |"
)
print()
print("| Camera Job Stage | avg ms/job |")
print("|---|---:|")
print(f"| manifest lookup | {fetch_pool['lookup_ms']:.3f} |")
print(f"| remote byte-range fetch | {fetch_pool['range_fetch_ms']:.3f} |")
print(f"| synthesize mini-MP4 | {fetch_pool['synthesize_ms']:.3f} |")
print(f"| store in shared cache | {fetch_pool['store_ms']:.3f} |")
print(f"| camera jobs | {fetch_pool['jobs']:.0f} |")
_print_memory_summary(memory_start, _memory_snapshot())
if args.include_decode:
timestamps = _timestamps(manifest, episodes, args.frames_per_episode, args.seed + 1)
_log(f"{label}: running parallel video fetch + decode-only")
parallel = run_parallel(
manifest,
data_root,
episodes,
timestamps,
byte_budget,
args.workers,
args.decode_workers,
args.frames_per_episode,
parquet_reader,
range_backend,
)
_log(f"{label}: running overlapped end-to-end")
overlapped = run_overlapped(
manifest,
data_root,
episodes,
timestamps,
byte_budget,
args.workers,
args.decode_workers,
args.frames_per_episode,
args.prefetch_ahead,
parquet_reader,
range_backend,
)
print(
f"| DECODE COMPARISON | {parallel['fetch_mbps']:.1f} | {parallel['fetch_episodes_s']:.2f} | "
f"{parallel['fetch_s']:.2f} | "
f"{_format_duration(benchmark_episode_count / parallel['fetch_episodes_s'])} | "
f"{_format_duration(dataset_episode_count / parallel['fetch_episodes_s'])} | "
f"{fetch_pool['avg_mb_miss']:.1f} | "
f"decoder open {parallel['decoder_ms_miss']:.1f} ms/miss, "
f"decode {parallel['decode_samples_s']:.1f} samples/s, parquet {parallel['parquet_s']:.2f}s |"
)
print(
f"| OVERLAPPED E2E | - | - | {overlapped['wall_s']:.2f} | - | - | "
f"{fetch_pool['avg_mb_miss']:.1f} | "
f"{overlapped['samples_s']:.1f} samples/s; video+decode "
f"{overlapped['video_wait_decode_s']:.2f}s, parquet {overlapped['parquet_wait_s']:.2f}s |"
)
def run_random_frame_strategy(
meta: LeRobotDatasetMetadata,
data_root: str,
args: argparse.Namespace,
*,
range_backend: str = "native-http",
label: str = "random-frames",
sidecar_path: str | None = None,
) -> None:
if args.frame_pool_size <= 0:
raise ValueError(f"frame-pool-size must be > 0, got {args.frame_pool_size}")
_log(f"starting_strategy: {label}")
memory_start = _memory_snapshot()
manifest_start = time.perf_counter()
dataset_episode_count = int(meta.total_episodes)
manifest_episode_count = args.manifest_episodes or dataset_episode_count
manifest_episode_count = min(manifest_episode_count, dataset_episode_count, args.num_episodes)
manifest = EpisodeVideoManifest.build(
meta,
data_root,
episode_indices=range(manifest_episode_count),
range_backend=range_backend,
workers=args.workers,
max_probe_bytes=args.max_probe_mb * 1024 * 1024,
sidecar_path=sidecar_path,
)
manifest_s = time.perf_counter() - manifest_start
_log(f"{label}: manifest_build_s={manifest_s:.2f}")
benchmark_episode_count = min(dataset_episode_count, args.num_episodes)
window_start = time.perf_counter()
windows = _sample_frame_windows(
manifest,
benchmark_episode_count=benchmark_episode_count,
frame_pool_size=args.frame_pool_size,
seed=args.seed,
)
window_s = time.perf_counter() - window_start
raw_bytes = sum(window.byte_length for window in windows)
useful_bytes = sum(window.useful_bytes for window in windows)
avg_decode_samples = sum(window.sample_hi - window.sample_lo + 1 for window in windows) / len(windows)
coalesce_start = time.perf_counter()
coalesced = _coalesce_windows(windows, args.coalesce_gap_kb * 1024)
coalesce_s = time.perf_counter() - coalesce_start
coalesced_bytes = sum(item.byte_length for item in coalesced)
_log(
f"{label}: fetching {len(coalesced)} coalesced ranges for {len(windows)} random frame targets "
f"({coalesced_bytes / 1024**2:.1f} MiB)"
)
fetcher = make_range_fetcher(data_root, range_backend=range_backend, workers=args.workers)
def read_range(item: CoalescedByteRange) -> int:
payload = fetcher.read_range(item.file_path, item.byte_offset, item.byte_length)
if len(payload) != item.byte_length:
raise OSError(f"Short read for {item.file_path}: expected {item.byte_length}, got {len(payload)}")
return len(payload)
fetch_start = time.perf_counter()
try:
with ThreadPoolExecutor(max_workers=args.workers) as pool:
fetched_bytes = sum(pool.map(read_range, coalesced))
finally:
fetcher.close()
fetch_s = time.perf_counter() - fetch_start
print(f"manifest_build_s: {manifest_s:.2f}")
print(f"strategy: {label}")
print(f"range_backend: {range_backend}")
print(f"mp4_sidecar: {sidecar_path or 'none'}")
print(f"data_root: {data_root}")
print(f"dataset_episodes: {dataset_episode_count}")
print(f"benchmark_episodes: {benchmark_episode_count}")
print(f"frame_targets: {len(windows)}")
print(f"cameras: {manifest.video_keys}")
print(f"coalesce_gap_kb: {args.coalesce_gap_kb}")
print()
print(
"| Track | fetch MB/s | frame targets/s | wall s | raw MiB | coalesced MiB | "
"ranges | avg KiB/range | avg KiB/frame | notes |"
)
print("|---|---:|---:|---:|---:|---:|---:|---:|---:|---|")
print(
f"| RANDOM FRAME WINDOWS | {fetched_bytes / fetch_s / 1024**2:.1f} | "
f"{len(windows) / fetch_s:.1f} | {fetch_s:.2f} | {raw_bytes / 1024**2:.1f} | "
f"{coalesced_bytes / 1024**2:.1f} | {len(coalesced)} | "
f"{coalesced_bytes / max(len(coalesced), 1) / 1024:.1f} | "
f"{coalesced_bytes / len(windows) / 1024:.1f} | "
f"{args.workers} workers, fetch-only, avg decode window {avg_decode_samples:.2f} samples |"
)
print()
print("| Local Stage | wall s |")
print("|---|---:|")
print(f"| compute frame windows from sidecar | {window_s:.3f} |")
print(f"| coalesce byte windows | {coalesce_s:.3f} |")
print(f"| raw byte windows | {len(windows)} |")
print(f"| coalesced byte ranges | {len(coalesced)} |")
print(f"| useful sample MiB | {useful_bytes / 1024**2:.1f} |")
_print_memory_summary(memory_start, _memory_snapshot())
def run_remote_strategy(
meta: LeRobotDatasetMetadata,
data_root: str,
args: argparse.Namespace,
parquet_reader: EpisodeParquetReader,
) -> None:
_log("starting_strategy: remote-decoder")
episodes = _episode_pool(int(meta.total_episodes), args.num_episodes, args.pool_size, args.seed)
timestamps = _timestamps_from_meta(meta, episodes, args.frames_per_episode, args.seed + 1)
_log("remote-decoder: running direct source MP4 decoder")
result = run_remote_decoder(
meta,
data_root,
episodes,
timestamps,
frames_per_episode=args.frames_per_episode,
decode_workers=args.decode_workers,
parquet_reader=parquet_reader,
)
print("strategy: remote-decoder")
print(f"data_root: {data_root}")
print(f"episodes: {episodes}")
print(f"cameras: {list(meta.video_keys)}")
print()
print("| Track | samples/s | notes |")
print("|---|---:|---|")
print(f"| REMOTE SEQUENTIAL | {result['sequential_samples_s']:.1f} | direct source MP4 decoder |")
print(
f"| REMOTE PARALLEL | {result['parallel_samples_s']:.1f} | "
f"direct source MP4 decoder, {args.decode_workers} workers |"
)
def main() -> None:
args = parse_args()
if args.strategy == "full":
args.strategy = "both"
data_root = args.data_root
if data_root.startswith("hf://") and not args.no_hub_branch_assert:
assert_hf_hub_range_cache_branch()
meta = LeRobotDatasetMetadata(args.repo_id, revision=args.revision)
meta.ensure_readable()
parquet_reader = EpisodeParquetReader(meta, data_root)
manifest_episode_count = args.manifest_episodes or int(meta.total_episodes)
manifest_episode_count = min(manifest_episode_count, int(meta.total_episodes), args.num_episodes)
sidecar_path = _find_or_download_sidecar(data_root, manifest_episode_count)
if sidecar_path is not None:
print(f"using_mp4_sidecar: {sidecar_path}")
if sidecar_path is not None and args.strategy == "both":
if args.include_decode:
run_remote_strategy(meta, data_root, args, parquet_reader)
print()
run_indexed_strategy(
meta,
data_root,
args,
parquet_reader,
range_backend="fsspec",
label="indexed-sidecar",
sidecar_path=str(sidecar_path),
)
print()
run_random_frame_strategy(
meta,
data_root,
args,
range_backend=args.random_frame_backend,
label=f"random-frames-{args.random_frame_backend}-sidecar",
sidecar_path=str(sidecar_path),
)
return
if sidecar_path is not None and args.strategy == "indexed":
run_indexed_strategy(
meta,
data_root,
args,
parquet_reader,
range_backend="fsspec",
label="indexed-sidecar",
sidecar_path=str(sidecar_path),
)
return
if sidecar_path is not None and args.strategy == "native-http":
print("using_indexed_sidecar_for_native_http: sidecar mode uses HfFileSystem range reads")
run_indexed_strategy(
meta,
data_root,
args,
parquet_reader,
range_backend="fsspec",
label="indexed-sidecar",
sidecar_path=str(sidecar_path),
)
return
if sidecar_path is not None and args.strategy == "random-frames":
run_random_frame_strategy(
meta,
data_root,
args,
range_backend=args.random_frame_backend,
label=f"random-frames-{args.random_frame_backend}-sidecar",
sidecar_path=str(sidecar_path),
)
return
if args.strategy == "both":
expected_sidecar = SIDECAR_CACHE_DIR / FULL_SIDECAR_NAME
expected_remote = _root_join(data_root, f"meta/mp4-sidecars/{FULL_SIDECAR_NAME}")
print(f"mp4_sidecar_missing_local: {expected_sidecar}")
print(f"mp4_sidecar_missing_remote: {expected_remote}")
print(
"build_mp4_sidecar: "
"uv run --no-sync python scripts/build_mp4_sidecar.py "
f"--workers {args.workers} --range-backend native-http --output {expected_sidecar}"
)
print("running_without_mp4_sidecar: indexed variants will build MP4 indexes online")
print()
if args.strategy in ("both", "indexed"):
run_indexed_strategy(
meta,
data_root,
args,
parquet_reader,
range_backend="fsspec",
label="indexed",
sidecar_path=None,
)
if args.strategy == "both":
print()
if args.strategy == "remote-decoder" or (args.strategy == "both" and args.include_decode):
run_remote_strategy(meta, data_root, args, parquet_reader)
if args.strategy == "both" and args.include_decode:
print()
if args.strategy in ("both", "native-http"):
run_indexed_strategy(
meta,
data_root,
args,
parquet_reader,
range_backend="native-http",
label="indexed-native-http",
sidecar_path=None,
)
if args.strategy == "both":
print()
if args.strategy in ("both", "random-frames"):
run_random_frame_strategy(
meta,
data_root,
args,
range_backend=args.random_frame_backend,
label=f"random-frames-{args.random_frame_backend}",
sidecar_path=None,
)
if __name__ == "__main__":
main()