fsspec / fsspec/filesystem_spec

HTTPFileSystem breaks when range requests are not supported

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Dominant language
Python
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Description

from fsspec.core import url_to_fs

ufs, url = url_to_fs("https://example.org/")
f = ufs.open("https://example.org/no-range-requests/data.txt")
f.seek(8192)
f.read(1)

Will raise # ValueError: The HTTP server doesn't appear to support range requests.

I was having trouble with cache options, but it turns out I was sending simplecache:: to the wrong place; this does work, but I don't really want to keep the seekable file around after the file is closed. Trying to be careful to open the file only once.

Contributor guide

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by running the reproducer against HTTPFileSystem with a URL that does not support range requests. Trace the seek and read path, including the cache options mentioned in the issue, to understand where the ValueError is raised. Done means the shown seek/read operation works without retaining a seekable file after close.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend, networking
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
42/100

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