add OOM message

[njzjz]

fix #748

[codecov-commenter]

Codecov Report

Merging #801 (c0f47ae) into devel (b145ca3) will increase coverage by 0.03%.
The diff coverage is 59.64%.

@@            Coverage Diff             @@
##            devel     #801      +/-   ##
==========================================
+ Coverage   73.96%   73.99%   +0.03%     
==========================================
  Files          84       85       +1     
  Lines        6588     6615      +27     
==========================================
+ Hits         4873     4895      +22     
- Misses       1715     1720       +5     

Impacted Files	Coverage Δ
deepmd/loss/tensor.py	51.81% <25.00%> (+0.44%)	⬆️
deepmd/loss/ener.py	47.57% <28.57%> (+0.23%)	⬆️
deepmd/entrypoints/train.py	65.25% <33.33%> (+0.29%)	⬆️
deepmd/infer/deep_pot.py	68.98% <50.00%> (+0.19%)	⬆️
deepmd/utils/sess.py	50.00% <50.00%> (ø)
deepmd/train/trainer.py	67.98% <54.54%> (+0.07%)	⬆️
deepmd/entrypoints/freeze.py	74.46% <66.66%> (+0.55%)	⬆️
deepmd/descriptor/loc_frame.py	97.60% <100.00%> (+0.01%)	⬆️
deepmd/descriptor/se_a.py	98.93% <100.00%> (+<0.01%)	⬆️
deepmd/descriptor/se_a_ef.py	54.83% <100.00%> (+0.24%)	⬆️
... and 9 more

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