Using placement groups while connecting to Ray cluster

Ray Clusters Kubernetes
1

I am experimenting with Ray’s gang scheduling and tried to follow example Placement Groups — Ray v2.0.0.dev0.

I have a Ray cluster running on k8 cluster and is connected to it from local notebook.
Following documentation, I am using the following code:

from ray.util.placement_group import (
placement_group,
placement_group_table,
remove_placement_group
)

Create a placement group.

cpu_bundle1 = {“CPU”: 2}
cpu_bundle2 = {“CPU”: 3}
pg = placement_group([cpu_bundle1, cpu_bundle2] , strategy=“STRICT_PACK”)

Wait until placement group is created.

ray.get(pg.ready())

Look at placement group states using this API.

print(placement_group_table(pg))

which gives me the following error:
RaySystemError: System error: Ray has not been started yet. You can start Ray with ‘ray.init()’.

Does this mean that I can’t create placement groups on the existing cluster?

2

You should be able to create placement groups on the existing cluster (even if they aren’t placeable it should not give an exception).

I believe this is an issue because the placement_group_table API is not supported with the Ray Client (ray.util.connect). Could you please file an issue for this on GitHub? cc @Ameer_Haj_Ali

3

Yeah, placement groups is currently not supported in ray client. There is an issue on github tracking this.

4

Thanks, is there an ETA for this?

5

Unfortunately, not yet. I’d probably say Q2/Q3.