NVIDIA / NVIDIA/apex

save_checkpoint corrupted

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Dominant language
Python
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Merged PRs (30d)
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Description

Saving a checkpoint when local_rank==0 will have one process per node writing to the same location and thus corrupt the checkpoint if nodes > 1

For example I got the error:

RuntimeError: storage has wrong size: expected 4249925191133211469 got 65536

Surely we would need to check if local_rank==0 and the node is the master-node, which the script currently doesn't do?

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Research direction

Inspect examples/imagenet/main_amp.py around line 253 and trace how checkpoint saving is gated during multi-node distributed training. Reproduce the save with more than one node and verify that only the master node writes the checkpoint and that the resulting file loads without the reported storage-size error.

Written by the indexing model from the issue text.

Assessment

Tech stack
python, pytorch
Domain
distributed-systems, machine-learning
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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