Bug in multithreaded file reading

[WWWWMMM]

🐛 Bug

https://github.com/dmlc/dgl/blob/master/examples/pytorch/metapath2vec/reading_data.py#L117

Set min_count=0 and num_workers=2, and comment line 117 - 119, it will get KeyError at line 115.Set num_workers = 0 will not see this bug.

To Reproduce

Steps to reproduce the behavior:

Expected behavior

Environment

• DGL Version (e.g., 1.0):
• Backend Library & Version (e.g., PyTorch 0.4.1, MXNet/Gluon 1.3):
• OS (e.g., Linux):
• How you installed DGL (conda, pip, source):
• Build command you used (if compiling from source):
• Python version:
• CUDA/cuDNN version (if applicable):
• GPU models and configuration (e.g. V100):
• Any other relevant information:

Additional context

[jermainewang]

It's a pretty old examples that are not being actively maintained (and likely won't be too). Are you using the latest DGL when getting this error? Maybe downgrade to older version could resolve the problem.

[github-actions]

This issue has been automatically marked as stale due to lack of activity. It will be closed if no further activity occurs. Thank you