[c10d] Turn off default non-blocking API mode to work around hang in NCCL 2.26 #154085
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…NCCL 2.26 (#154055) Work around issues like #153960, #152623 NCCL 2.26 seems to introduce random hang in non-blocking API mode. This PR opts out of non-blocking mode to work around it. Previously torch turned it on by default in eager init (i.e. `device_id` passed) to avoid init overhead. Pull Request resolved: #154055 Approved by: https://github.com/atalman (cherry picked from commit 87fc5af)
This was referenced May 22, 2025
🔗 Helpful Links🧪 See artifacts and rendered test results at hud.pytorch.org/pr/154085
Note: Links to docs will display an error until the docs builds have been completed. ✅ No FailuresAs of commit fecbe87 with merge base 924a247 ( This comment was automatically generated by Dr. CI and updates every 15 minutes. |
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Stack from ghstack (oldest at bottom):
Work around issues like #153960, #152623
NCCL 2.26 seems to introduce random hang in non-blocking API mode. This PR opts out of non-blocking mode to work around it. Previously torch turned it on by default in eager init (i.e.
device_idpassed) to avoid init overhead.cc @H-Huang @awgu @wanchaol @fegin @fduwjj @wz337 @wconstab @d4l3k