This is the 1st PR to remove the code path of multiple core workers in one process. This PR is aiming to remove the flags and APIs related to `num_workers`.
After this PR checking in, we needn't to consider the multiple core workers any longer.
The further following PRs are related to the deeper logic refactor, like eliminating the gap between core worker and core worker process, removing the logic related to multiple workers from workerpool, gcs and etc.
**BREAK CHANGE**
This PR removes these APIs:
- Ray.wrapRunnable();
- Ray.wrapCallable();
- Ray.setAsyncContext();
- Ray.getAsyncContext();
And the following APIs are not allowed to invoke in a user-created thread in local mode:
- Ray.getRuntimeContext().getCurrentActorId();
- Ray.getRuntimeContext().getCurrentTaskId()
Note that this PR shouldn't be merged to 1.x.
