`metric.compute` throws `ArrowInvalid` error
Hmm might be related to what we are solving in #564 Could you try to update to `datasets>=1.0.0` (we changed the name of the library) and try again ?
If is was related to the distributed setup settings it must be fixed.
If it was related to empty metric inputs it's going to be fixed in #654  Closing this one as it was fixed in #654 
Feel free to re-open if you have other questions
I get the following error with `rouge.compute`. It happens only with distributed training, and it occurs randomly I can't easily reproduce it. This is using `nlp==0.4.0`

```
  File "/home/beltagy/trainer.py", line 92, in validation_step
    rouge_scores = rouge.compute(predictions=generated_str, references=gold_str, rouge_types=['rouge2', 'rouge1', 'rougeL'])
  File "/home/beltagy/miniconda3/envs/allennlp/lib/python3.7/site-packages/nlp/metric.py", line 224, in compute
    self.finalize(timeout=timeout)
  File "/home/beltagy/miniconda3/envs/allennlp/lib/python3.7/site-packages/nlp/metric.py", line 213, in finalize
    self.data = Dataset(**reader.read_files(node_files))
  File "/home/beltagy/miniconda3/envs/allennlp/lib/python3.7/site-packages/nlp/arrow_reader.py", line 217, in read_files
    dataset_kwargs = self._read_files(files=files, info=self._info, original_instructions=original_instructions)
  File "/home/beltagy/miniconda3/envs/allennlp/lib/python3.7/site-packages/nlp/arrow_reader.py", line 162, in _read_files
    pa_table: pa.Table = self._get_dataset_from_filename(f_dict)
  File "/home/beltagy/miniconda3/envs/allennlp/lib/python3.7/site-packages/nlp/arrow_reader.py", line 276, in _get_dataset_from_filename
    f = pa.ipc.open_stream(mmap)
  File "/home/beltagy/miniconda3/envs/allennlp/lib/python3.7/site-packages/pyarrow/ipc.py", line 173, in open_stream
    return RecordBatchStreamReader(source)
  File "/home/beltagy/miniconda3/envs/allennlp/lib/python3.7/site-packages/pyarrow/ipc.py", line 64, in __init__
    self._open(source)
  File "pyarrow/ipc.pxi", line 469, in pyarrow.lib._RecordBatchStreamReader._open
  File "pyarrow/error.pxi", line 122, in pyarrow.lib.pyarrow_internal_check_status
  File "pyarrow/error.pxi", line 84, in pyarrow.lib.check_status
pyarrow.lib.ArrowInvalid: Tried reading schema message, was null or length 0
```