Skip to content

fix: use sequential read instead of seek for multipart uploads on Windows #3912

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
s-zx wants to merge 1 commit into
base: main
Choose a base branch
from
Open

fix: use sequential read instead of seek for multipart uploads on Windows #3912

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
48 changes: 25 additions & 23 deletions src/huggingface_hub/cli/lfs.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,6 @@
from huggingface_hub.lfs import LFS_MULTIPART_UPLOAD_COMMAND

from ..utils import get_session, hf_raise_for_status, logging
from ..utils._lfs import SliceFileObj


logger = logging.get_logger(__name__)
Expand Down Expand Up @@ -139,29 +138,32 @@ def lfs_multipart_upload() -> None:
parts = []
with open(filepath, "rb") as file:
for i, presigned_url in enumerate(presigned_urls):
with SliceFileObj(
file,
seek_from=i * chunk_size,
read_limit=chunk_size,
) as data:
r = get_session().put(presigned_url, data=data)
hf_raise_for_status(r)
parts.append(
{
"etag": r.headers.get("etag"),
"partNumber": i + 1,
}
)
# In order to support progress reporting while data is uploading / downloading,
# the transfer process should post messages to stdout
write_msg(
{
"event": "progress",
"oid": oid,
"bytesSoFar": (i + 1) * chunk_size,
"bytesSinceLast": chunk_size,
}
# Read chunk sequentially instead of using SliceFileObj + seek.
# On Windows, file.seek() with offset >= 2GB can fail due to 32-bit
# signed integer limits in some APIs (see issue #3871).
chunk_data = file.read(chunk_size)
Copy link
Copy Markdown
Contributor

@Wauplin Wauplin Mar 12, 2026

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

This will load the entire chunk_data into memory which we absolutely want to avoid on large files.

if not chunk_data:
raise ValueError(
f"Unexpected end of file while reading part {i + 1} of multipart upload"
)
r = get_session().put(presigned_url, data=chunk_data)
hf_raise_for_status(r)
parts.append(
{
"etag": r.headers.get("etag"),
"partNumber": i + 1,
}
)
# In order to support progress reporting while data is uploading / downloading,
# the transfer process should post messages to stdout
write_msg(
{
"event": "progress",
"oid": oid,
"bytesSoFar": (i + 1) * chunk_size,
"bytesSinceLast": chunk_size,
}
)

r = get_session().post(
completion_url,
Expand Down
22 changes: 12 additions & 10 deletions src/huggingface_hub/lfs.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,6 @@
logging,
validate_hf_hub_args,
)
from .utils._lfs import SliceFileObj
from .utils.sha import sha256, sha_fileobj


Expand Down Expand Up @@ -383,13 +382,16 @@ def _upload_parts_iteratively(
headers = []
with operation.as_file(with_tqdm=True) as fileobj:
for part_idx, part_upload_url in enumerate(sorted_parts_urls):
with SliceFileObj(
fileobj,
seek_from=chunk_size * part_idx,
read_limit=chunk_size,
) as fileobj_slice:
# S3 might raise a transient 500 error -> let's retry if that happens
part_upload_res = http_backoff("PUT", part_upload_url, data=fileobj_slice)
hf_raise_for_status(part_upload_res)
headers.append(part_upload_res.headers)
# Read chunk sequentially instead of using SliceFileObj + seek.
# On Windows, file.seek() with offset >= 2GB can fail due to 32-bit
# signed integer limits in some APIs (see issue #3871).
chunk_data = fileobj.read(chunk_size)
if not chunk_data:
raise ValueError(
f"Unexpected end of file while reading part {part_idx + 1} of multipart upload"
)
# S3 might raise a transient 500 error -> let's retry if that happens
part_upload_res = http_backoff("PUT", part_upload_url, data=chunk_data)
hf_raise_for_status(part_upload_res)
headers.append(part_upload_res.headers)
return headers # type: ignore
Loading