Release GIL during DDP construction. #40877
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Summary: Pull Request resolved: pytorch#40495 As part of debugging flaky ddp_under_dist_autograd tests, I realized we were running into the following deadlock. 1) Rank 0 would go into DDP construction, hold GIL and wait for broadcast in DDP construction. 2) Rank 3 is a little slower and performs an RRef fetch call before the DDP construction. 3) The RRef fetch call is done on Rank 0 and tries to acquire GIL. 4) We now have a deadlock since Rank 0 is waiting for Rank 3 to enter the collective and Rank 3 is waiting for Rank 0 to release GIL. ghstack-source-id: 106534442 Test Plan: 1) Ran ddp_under_dist_autograd 500 times. 2) waitforbuildbot Differential Revision: D22205180 fbshipit-source-id: 6afd55342e801b9edb9591ff25158a244a8ea66a
mrshenli
approved these changes
Jul 1, 2020
💊 CI failures summary and remediationsAs of commit 6be6fd3 (more details on the Dr. CI page):
XLA failureJob pytorch_xla_linux_bionic_py3_6_clang9_build is failing. Please create an issue with title prefixed by This comment was automatically generated by Dr. CI (expand for details).Follow this link to opt-out of these comments for your Pull Requests.Please report bugs/suggestions on the GitHub issue tracker or post in the (internal) Dr. CI Users group. This comment has been revised 1 time. |
seemethere
approved these changes
Jul 1, 2020
|
Going to go ahead and merge this |
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Cherry-pick #40495 into 1.6
As part of debugging flaky ddp_under_dist_autograd tests, I realized
we were running into the following deadlock.
DDP construction.
construction.
collective and Rank 3 is waiting for Rank 0 to release GIL.
Test Plan: