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[release/2.15][c10d][nccl2] Abort timed-out groups on every rank in timeout tests (#200371) - #3854
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pragupta merged 1 commit intoOct 26, 2026
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…ytorch#200371) Fixes pytorch#200326 Root cause: in the nccl2 timeout tests rank 0's communicator times out and is aborted, while the other ranks call destroy_process_group(). NCCL 2.31+ runs bootstrapIntraNodeBarrier in commDestroySync unless the comm was aborted, so the survivors wait forever for rank 0 at the teardown barrier and the test hangs until the class timeout. Fix: every rank aborts the timed-out group via _abort_process_group() instead of a graceful destroy, in the five tests that leave a timed-out subgroup behind. Test plan: PYTHONPATH=/tmp/flk/nccl232 python test/distributed/test_c10d_nccl2.py -k WatchdogNoTearDown -k BlockingWait -k DumpOnTimeout -k DumpTimeoutBound # NCCL 2.32.3, 15x pass; hung before python test/distributed/test_c10d_nccl2.py -k WatchdogNoTearDown -k BlockingWait -k DumpOnTimeout -k DumpTimeoutBound # NCCL 2.30.7, 5x pass Authored with an AI assistant (Claude). Pull Request resolved: pytorch#200371 Approved by: https://github.com/fduwjj (cherry picked from commit e63e88f)
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…imeout tests (pytorch#200371) (#3854) Fixes pytorch#200326 Root cause: in the nccl2 timeout tests rank 0's communicator times out and is aborted, while the other ranks call destroy_process_group(). NCCL 2.31+ runs bootstrapIntraNodeBarrier in commDestroySync unless the comm was aborted, so the survivors wait forever for rank 0 at the teardown barrier and the test hangs until the class timeout. Fix: every rank aborts the timed-out group via _abort_process_group() instead of a graceful destroy, in the five tests that leave a timed-out subgroup behind. Test plan: PYTHONPATH=/tmp/flk/nccl232 python test/distributed/test_c10d_nccl2.py -k WatchdogNoTearDown -k BlockingWait -k DumpOnTimeout -k DumpTimeoutBound # NCCL 2.32.3, 15x pass; hung before python test/distributed/test_c10d_nccl2.py -k WatchdogNoTearDown -k BlockingWait -k DumpOnTimeout -k DumpTimeoutBound # NCCL 2.30.7, 5x pass Authored with an AI assistant (Claude). Pull Request resolved: pytorch#200371 Approved by: https://github.com/fduwjj (cherry picked from commit e63e88f) Co-authored-by: Tristan Rice <rice@fn.lc>
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Fixes pytorch#200326
Root cause: in the nccl2 timeout tests rank 0's communicator times out and is aborted, while the other ranks call destroy_process_group(). NCCL 2.31+ runs bootstrapIntraNodeBarrier in commDestroySync unless the comm was aborted, so the survivors wait forever for rank 0 at the teardown barrier and the test hangs until the class timeout.
Fix: every rank aborts the timed-out group via _abort_process_group() instead of a graceful destroy, in the five tests that leave a timed-out subgroup behind.
Test plan:
PYTHONPATH=/tmp/flk/nccl232 python test/distributed/test_c10d_nccl2.py -k WatchdogNoTearDown -k BlockingWait -k DumpOnTimeout -k DumpTimeoutBound # NCCL 2.32.3, 15x pass; hung before
python test/distributed/test_c10d_nccl2.py -k WatchdogNoTearDown -k BlockingWait -k DumpOnTimeout -k DumpTimeoutBound # NCCL 2.30.7, 5x pass
Authored with an AI assistant (Claude).
Pull Request resolved: pytorch#200371 Approved by: https://github.com/fduwjj
(cherry picked from commit e63e88f)