[experiment] missing default_experiment-1-0.arrow
Right, to clarify, I meant it'd be good to have it sorted on the library side and not requiring the user to figure it out. This is too complex and error-prone and if not coded correctly the bug will be intermittent which is even worse.

Oh I guess I wasn't clear in my message - in no way I'm proposing that we use this workaround code - I was just showing what I had to do to make it work.

We are on the same page.

> The changes you are proposing Stas are making the code less readable and also concatenate all the predictions and labels number_of_processes times I believe, which is not going to make the metric computation any faster.

And yes, this is another problem that my workaround introduces. Thank you for pointing it out, @sgugger 

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. 
 Right, to clarify, I meant it'd be good to have it sorted on the library side and not requiring the user to figure it out. This is too complex and error-prone and if not coded correctly the bug will be intermittent which is even worse.

Oh I guess I wasn't clear in my message - in no way I'm proposing that we use this workaround code - I was just showing what I had to do to make it work.

We are on the same page.

> The changes you are proposing Stas are making the code less readable and also concatenate all the predictions and labels number_of_processes times I believe, which is not going to make the metric computation any faster.

And yes, this is another problem that my workaround introduces. Thank you for pointing it out, @sgugger 
