Use NCCL bootsrap backend for TP communication overlaps
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---

Your code was analyzed with PyLint. The following annotations have been identified:

```
************* Module nemo.collections.nlp.models.language_modeling.megatron_base_model
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:103:0: C0301: Line too long (149/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:111:0: C0301: Line too long (134/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:253:0: C0301: Line too long (125/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:271:0: C0301: Line too long (120/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:346:0: C0301: Line too long (133/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:606:0: C0301: Line too long (123/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:661:0: C0301: Line too long (153/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:833:0: C0301: Line too long (122/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:961:0: C0301: Line too long (121/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:980:0: C0301: Line too long (136/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1097:0: C0301: Line too long (195/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1154:0: C0301: Line too long (135/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1203:0: C0301: Line too long (120/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1286:0: C0301: Line too long (128/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:330:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:461:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:466:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:699:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:751:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:922:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1026:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1261:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1292:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1296:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_base_model.py:1300:4: C0116: Missing function or method docstring (missing-function-docstring)
************* Module nemo.collections.nlp.models.language_modeling.megatron_gpt_model
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:327:0: C0301: Line too long (149/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:367:0: C0301: Line too long (136/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:413:0: C0301: Line too long (126/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:460:0: C0301: Line too long (122/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:791:0: C0301: Line too long (131/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1106:0: C0301: Line too long (146/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1127:0: C0301: Line too long (168/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1335:0: C0301: Line too long (122/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1392:0: C0301: Line too long (140/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1573:0: C0301: Line too long (132/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1574:0: C0301: Line too long (136/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1576:0: C0301: Line too long (159/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1747:0: C0301: Line too long (128/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1767:0: C0301: Line too long (140/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1775:0: C0301: Line too long (155/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1796:0: C0301: Line too long (141/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1866:0: C0301: Line too long (125/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1893:0: C0301: Line too long (134/119) (line-too-long)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:140:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:153:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:179:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:198:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:245:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:283:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:287:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:299:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:307:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:469:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:472:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:701:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:705:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:787:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1104:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1177:12: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1226:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1254:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1405:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1540:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1548:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1557:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1841:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:1994:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:2001:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:2007:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:20:0: W0611: Unused fields imported from dataclasses (unused-import)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:27:0: W0611: Unused OmegaConf imported from omegaconf (unused-import)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:30:0: W0611: Unused _DataFetcherWrapper imported from pytorch_lightning.loops.fetchers (unused-import)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:72:0: W0611: Unused activation_to_func imported from nemo.collections.nlp.parts.utils_funcs (unused-import)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:81:4: W0611: Unused megatron.core imported as core (unused-import)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:82:4: W0611: Unused tensor_parallel imported from megatron.core (unused-import)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:101:4: W0611: Unused init_method_normal imported from megatron.core.utils (unused-import)
nemo/collections/nlp/models/language_modeling/megatron_gpt_model.py:101:4: W0611: Unused scaled_init_method_normal imported from megatron.core.utils (unused-import)
************* Module nemo.collections.nlp.parts.nlp_overrides
nemo/collections/nlp/parts/nlp_overrides.py:211:0: C0301: Line too long (140/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:216:0: C0301: Line too long (149/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:232:0: C0301: Line too long (123/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:424:0: C0301: Line too long (136/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:510:0: C0301: Line too long (152/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:730:0: C0301: Line too long (140/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:735:0: C0301: Line too long (149/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:1001:0: C0301: Line too long (128/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:1005:0: C0301: Line too long (141/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:1009:0: C0301: Line too long (149/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:1066:0: C0301: Line too long (135/119) (line-too-long)
nemo/collections/nlp/parts/nlp_overrides.py:1193:0: C0301: Line too long (121/119) (line-too-long)
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nemo/collections/nlp/parts/nlp_overrides.py:247:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:380:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:425:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:602:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:618:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:637:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:878:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:997:0: C0115: Missing class docstring (missing-class-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:1682:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:1770:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/collections/nlp/parts/nlp_overrides.py:18:0: W0611: Unused import re (unused-import)
nemo/collections/nlp/parts/nlp_overrides.py:106:4: W0611: Unused tensorstore imported from megatron.core.dist_checkpointing.strategies (unused-import)
************* Module nemo.lightning._strategy_lib
nemo/lightning/_strategy_lib.py:563:0: C0301: Line too long (130/119) (line-too-long)
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nemo/lightning/_strategy_lib.py:140:0: C0116: Missing function or method docstring (missing-function-docstring)
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nemo/lightning/_strategy_lib.py:516:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/_strategy_lib.py:588:0: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/_strategy_lib.py:601:4: C0115: Missing class docstring (missing-class-docstring)
************* Module nemo.lightning.pytorch.callbacks.megatron_comm_overlap
nemo/lightning/pytorch/callbacks/megatron_comm_overlap.py:81:0: C0301: Line too long (121/119) (line-too-long)
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nemo/lightning/pytorch/callbacks/megatron_comm_overlap.py:280:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/callbacks/megatron_comm_overlap.py:284:4: C0116: Missing function or method docstring (missing-function-docstring)
nemo/lightning/pytorch/callbacks/megatron_comm_overlap.py:288:4: C0116: Missing function or method docstring (missing-function-docstring)

-----------------------------------
Your code has been rated at 9.59/10
```

---

Thank you for improving NeMo's documentation! @erhoo82 CI is ready; you can merge this.
# What does this PR do ?

Use NCCL bootsrap backend and skip creating mpi process group.

**Collection**: [Note which collection this PR will affect]

# Changelog 
- Add specific line by line info of high level changes in this PR.

# Usage
- The default backend is `nccl`, where no need to create mpi proc group

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**PR Type**:
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# Additional Information
* Related to # (issue)
