git commit -m "Fix NCCL timeout issues in async checkpoint saving

[Abenez3r]

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What does this PR do ?

Fixes NCCL timeout issues during async checkpoint saving for large models

Collection: Core

Changelog

• Add configure_nccl_for_checkpointing() function to set appropriate NCCL timeouts
• Implement automatic fallback from async to sync saving on NCCL timeouts
• Configure NCCL environment variables for large model checkpoint operations

Testing:

• Verified NCCL configuration function sets environment variables correctly
• Confirmed fallback logic triggers on timeout/NCCL error patterns
• Tested in local development environment

Usage

• N/A

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Additional Information

• Fix for Save checkpoint too slow (more than 1500s) when training Qwen3 235B #14576 (NCCL timeout portion)

[Abenez3r]

@ericharper @titu1994 Could you review this core checkpoint fix?