Revisit huggingface cache policy

[elronbandel]

Changes:

1. Make loading of external hugginface datasets be cached be default (by huggingface cache mechanism)
2. Make re-loading of unitxt dataset not cached by default (unless user asked for it explicitly)
3. Make processing of external huggingface datasets be without streaming unless specified explicitly

[dafnapension]

Why? Once the files are downloaded to local file system, what benefit you get here?

[elronbandel]

You dont, It just dosent work otherwise. We should base this loader on dictionary loader.

[dafnapension]

in:

unitxt/src/unitxt/loaders.py

Line 293 in c863ee7

dataset[split] = dataset[split].to_iterable_dataset()

once the dataset is loaded from HF (as dataset, not iterable_dataset) why change it to iterable_dataset? I got the impression that each move of each instance in iterable_dataset incurs much energy (probably to preserve a state or something). Does Unitxt needs the dataset as iterable?

[assaftibm]

You can use this code to compare the loading time of HF and UT:

import os.path
import shutil
from time import time

from datasets import load_dataset as hf_load_dataset
from unitxt.api import load_dataset
import unitxt

path = "hf_cache"
# path = "/home/dafna/.cache/huggingface"

if os.path.exists(path):
    shutil.rmtree(path)
cache_dir=path
t0 = time()
ds = hf_load_dataset("PrimeQA/clapnq_passages", cache_dir=path)
print(f"hf ds: {ds}")
t1 = time()
instances = list(ds["train"])
t2 = time()
print(f"num of instances in ds = {len(instances)}")
print(f"from start to after load_dataset: {t1-t0}")
print(f"from after load_dataset to after list of ds = {t2-t1}")
print()
if os.path.exists(path):
    shutil.rmtree(path)

# disable the cache for hf datasets
unitxt.settings.disable_hf_datasets_cache=True
t0 = time()
ds = load_dataset('card=cards.rag.documents.clap_nq.en')
t1 = time()
instances = list(ds["train"])
t2 = time()
print(f"num of instances in ds = {len(instances)}")
print(f"from start to after load_dataset: {t1-t0}")
print(f"from after load_dataset to after list of ds = {t2-t1}")

[elronbandel]

@assaftibm this PR is not yet the solution to the problem you pointed out. We broke it up to two PRs as it is global changes which we want to introduce and test gradually.