[experiment] missing default_experiment-1-0.arrow
Thank you for clarifying that the metrics files are to be found elsewhere, @lhoestq 

> The cache at ~/.cache/huggingface/metrics stores the users data for metrics computations (hence the arrow files).

could it be renamed to reflect that? otherwise it misleadingly suggests that it's the metrics. Perhaps `~/.cache/huggingface/metrics-user-data`?

And there are so many `.lock` files w/o corresponding files under `~/.cache/huggingface/metrics/`. Why are they there? 

for example after I wipe out the dir completely and do one training I end up with:
```
~/.cache/huggingface/metrics/sacrebleu/default/default_experiment-1-0.arrow.lock
```
what is that lock file locking when nothing is running?
the original report was pretty bad and incomplete - my apologies!

Please see the complete version here: https://github.com/huggingface/datasets/issues/1942#issuecomment-786336481

------------

As mentioned here https://github.com/huggingface/datasets/issues/1939 metrics don't get cached, looking at my local `~/.cache/huggingface/metrics` - there are many `*.arrow.lock` files but zero metrics files.

w/o the network I get:
```
FileNotFoundError: [Errno 2] No such file or directory: '~/.cache/huggingface/metrics/sacrebleu/default/default_experiment-1-0.arrow
```
there is just `~/.cache/huggingface/metrics/sacrebleu/default/default_experiment-1-0.arrow.lock`

I did run the same `run_seq2seq.py` script on the instance with network and it worked just fine, but only the lock file was left behind.

this is with master.

Thank you.
[experiment] missing default_experiment-1-0.arrow 
 the original report was pretty bad and incomplete - my apologies!

Please see the complete version here: https://github.com/huggingface/datasets/issues/1942#issuecomment-786336481

------------

As mentioned here https://github.com/huggingface/datasets/issues/1939 metrics don't get cached, looking at my local `~/.cache/huggingface/metrics` - there are many `*.arrow.lock` files but zero metrics files.

w/o the network I get:
```
FileNotFoundError: [Errno 2] No such file or directory: '~/.cache/huggingface/metrics/sacrebleu/default/default_experiment-1-0.arrow
```
there is just `~/.cache/huggingface/metrics/sacrebleu/default/default_experiment-1-0.arrow.lock`

I did run the same `run_seq2seq.py` script on the instance with network and it worked just fine, but only the lock file was left behind.

this is with master.

Thank you. 
 Thank you for clarifying that the metrics files are to be found elsewhere, @lhoestq 

> The cache at ~/.cache/huggingface/metrics stores the users data for metrics computations (hence the arrow files).

could it be renamed to reflect that? otherwise it misleadingly suggests that it's the metrics. Perhaps `~/.cache/huggingface/metrics-user-data`?

And there are so many `.lock` files w/o corresponding files under `~/.cache/huggingface/metrics/`. Why are they there? 

for example after I wipe out the dir completely and do one training I end up with:
```
~/.cache/huggingface/metrics/sacrebleu/default/default_experiment-1-0.arrow.lock
```
what is that lock file locking when nothing is running?