UnboundLocalError: cannot access local variable 'batch_idx' where it is not associated with a value about ragatouille

[filippo82]

This seems to be a bug in ColBERT.

If for some reason the for batch_idx, BatchSteps in zip(range(start_batch_idx, config.maxsteps), reader): loop is not executed, then batch_idx is not defined. This will cause the UnboundLocalError: cannot access local variable 'batch_idx' where it is not associated with a value.

[tm17-abcgen]

Solved it by just initializing batch_idx in the colbert library, not sure if its right though, but not getting the error anymore with that (in /colbert/training/training.py):
@okhat

start_batch_idx = 0
batch_idx = start_batch_idx

# if config.resume:
#     assert config.checkpoint is not None
#     start_batch_idx = checkpoint['batch']

#     reader.skip_to_batch(start_batch_idx, checkpoint['arguments']['bsize'])

for batch_idx, BatchSteps in zip(range(start_batch_idx, config.maxsteps), reader):

[bclavie]

Since your query count is quite low, this could be a problem similar to the one here stanford-futuredata/ColBERT#118? Does it still occur if you use a lower batch size? (without modifying the code in the upstream ColBERT)

[tm17-abcgen]

Setting batch size to 4 or 8 also showed the same problem. What is weird is that sometimes this problem occurs, and sometimes not, until batch_idx is initialized before the loop manually.

[JoshuaPurtell]

Yeah, this often occurs if there are no valid triplets to train on.

[JoshuaPurtell]

Here's a PR to colbert that I believe should alleviate this issue in many cases.

stanford-futuredata/ColBERT#312

[dmh43]

Shouldnt this be easy to catch earlier up the call stack and emit a warning or error?