Increase testing granularity for speedup

[ddobrinskiy]

Using 9 batches instead of 3:

Current setup of 3 batches means that 20+ notebooks fall into the [5-7] batch and it takes 9minutes to test all the notebooks, example: https://github.com/fastai/fastai/pull/3235/checks?check_run_id=1969103831

With minimal code changes, we can split notebooks into 9 batches instead of 3, which should speed-up testing

upd: with new configuration, actual notebook testing takes at most 1m20s (excluding docker setup, cache download, et cetera)

[ddobrinskiy]

Hmmm, not sure what the problem is.

The tests fail for nbs/04_data.external.ipynb saying that file is not found, full traceback below.

The CALTECH url is reachable at the moment. https://s3.amazonaws.com/fast-ai-imageclas/caltech_101.tgz

Reading from the notebook, I get a feeling that maybe this cell should not be present anyway?

Error in /__w/fastai/fastai/nbs/04_data.external.ipynb:
An error occurred while executing the following cell:
------------------
url = URLs.CALTECH_101
untar_data(url)
_add_check(url, URLs.path(url))
------------------

rror in /__w/fastai/fastai/nbs/04_data.external.ipynb:
An error occurred while executing the following cell:
------------------
url = URLs.CALTECH_101
untar_data(url)
_add_check(url, URLs.path(url))
------------------

---------------------------------------------------------------------------
FileNotFoundError                         Traceback (most recent call last)
/__w/fastai/fastai/fastai/data/external.py in <module>
      1 url = URLs.CALTECH_101
      2 untar_data(url)
----> 3 _add_check(url, URLs.path(url))

/__w/fastai/fastai/fastai/data/external.py in _add_check(url, fname)
      3     "Internal function to update the internal check file with `url` and check on `fname`."
      4     checks = json.load(open(Path(__file__).parent/'checks.txt', 'r'))
----> 5     checks[url] = _check_file(fname)
      6     json.dump(checks, open(Path(__file__).parent/'checks.txt', 'w'), indent=2)

/__w/fastai/fastai/fastai/data/external.py in _check_file(fname)
      7 def _check_file(fname):
      8     "internal function to get the hash of the local file at `fname`."
----> 9     size = os.path.getsize(fname)
     10     with open(fname, "rb") as f: hash_nb = hashlib.md5(f.read(2**20)).hexdigest()
     11     return [size,hash_nb]

/usr/lib/python3.8/genericpath.py in getsize(filename)
     48 def getsize(filename):
     49     """Return the size of a file, reported by os.stat()."""
---> 50     return os.stat(filename).st_size
     51 
     52 

FileNotFoundError: [Errno 2] No such file or directory: '/github/home/.fastai/archive/caltech_101.tgz'

[ddobrinskiy]

On further investigation, I can see that the cell in question was added (commit) by @jph00 couple months ago.

I don't understand why it did not fail for other PRs

[jph00]

Thanks!