* Precede ray.get with ray.wait.

* Trigger checkpoint deletes locally in Trainable

* Clean-up code.

* Minor changes.

* Track best checkpoint so far again

* Pulled checkpoint GC out of Trainable.

* Added comments, error logging.

* Immediate pull after checkpoint taken; rsync source delete on pull

* Minor doc fixes

* Fix checkpoint manager bug

* Fix bugs, tests, formatting

* Fix bugs, feature flag for force sync.

* Fix test.

* Fix minor bugs: clear proc and less verbose sync_on_checkpoint warnings.

* Fix bug: update IP of last_result.

* Fixed message.

* Added a lot of logging.

* Changes to ray trial executor.

* More bug fixes (logging after failure), better logging.

* Fix richards bug and logging

* Add comments.

* try-except

* Fix heapq bug.

* .

* Move handling of no available trials to ray_trial_executor (#1)

* Fix formatting bug, lint.

* Addressed Richard's comments

* Revert tests.

* fix rebase

* Fix trial location reporting.

* Fix test

* Fix lint

* Rebase, use ray.get w/ timeout, lint.

* lint

* fix rebase

* Address richard's comments

…unicator caching (ray-project#12935)

* other collectives all work

* auto-linting

* mannual linting #1

* mannual linting 2

* bugfix

* add send/recv point-to-point calls

* add some initial code for communicator caching

* auto linting

* optimize imports

* minor fix

* fix unpassed tests

* support more dtypes

* rerun some distributed tests for send/recv

* linting

* WIP.

* Fix.

* Fix.

* Fix.