[1.5 Release][RPC Reliability] RRef Idempotency and RPC Retry enablement (#33636)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33636
Fixes https://github.com/pytorch/pytorch/issues/32119, https://github.com/pytorch/pytorch/issues/26116,
https://github.com/pytorch/pytorch/issues/33072
Makes RRef control messages idempotent and enables sending with retries for distributed autograd cleanup and RRef internal messages.
In order to effectively test whether these RRef and distributed autograd cleanup work with network failures/retries, I implemented an RPC Agent with a faulty send function, and enabled running tests using this as a third backend (in addition to Thrift and PGA). The tests using this backend are in a separate class (the test cases are similar but with minor changes to ensure short-running tests wait for retried RPCs to finish).
This faulty RPC Agent is pretty configurable. The tests can configure which messages types to fail, and how many messages to fail, but going forward, other RPC functionality can be overriden with faulty methods to test with failures injected.
Differential Revision: D20019236
fbshipit-source-id: 540a977e96b2e29aa0393ff12621fa293fe92b48
