pytorch

5a10ee71 - [Reland] TCPStore add watchKey method and new listener thread (#56217)

[Reland] TCPStore add watchKey method and new listener thread (#56217) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/56217 Reland of https://github.com/pytorch/pytorch/pull/54264 Changes: - Update socket send() to use flag MSG_NOSIGNAL to prevent SIGPIPE because error in return is already capturad - Update watchKey to block until callback has been registered on master. - Fix race condition in testWatchKeyCallback which caused flaky test failures. Test: Ran TCPStoreTest 100 times locally with no errors, running [ci-all tests](https://github.com/pytorch/pytorch/pull/56219) Test Plan: Imported from OSS Reviewed By: mrshenli Differential Revision: D27824802 Pulled By: H-Huang fbshipit-source-id: c32230ce726d7d848b9896a63aa52b8eb04a0a2d