Functions for flushing done tasks and evicted objects.

[robertnishihara]

This lets you flush metadata from Redis for done tasks and evicted objects.

ray.experimental.flush_done_tasks_unsafe()
ray.experimental.flush_evicted_objects_unsafe()

If these functions are too slow, they can be called from within a remote function running in the background.

You can also flush each shard individually, for example

@ray.remote
def flush_task_shard(i):
    ray.experimental._flush_finished_tasks_unsafe_shard(i)

@ray.remote
def flush_object_shard(i):
    ray.experimental._flush_evicted_objects_unsafe_shard(i)

task_flushing = [flush_task_shard.remote(i) for i in range(len(ray.global_state.redis_clients))]
object_flushing = [flush_object_shard.remote(i) for i in range(len(ray.global_state.redis_clients))]
%time ray.get(task_flushing + object_flushing)

The latter should get faster as the number of Redis shards is increased.

cc @TWAnthony

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/5316/
Test FAILed.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/5319/
Test FAILed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/5320/
Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/5325/
Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/5408/
Test PASSed.

[AmplabJenkins]

Test PASSed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/5445/
Test PASSed.

[AmplabJenkins]

Test FAILed.
Refer to this link for build results (access rights to CI server needed):
https://amplab.cs.berkeley.edu/jenkins//job/Ray-PRB/5464/
Test FAILed.