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[Bugfix][Ray] Fix RayExecutorV2 actor name collision with DP > 1 #40398

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vllm-bot merged 2 commits into from
May 3, 2026
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[Bugfix][Ray] Fix RayExecutorV2 actor name collision with DP > 1 #40398

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Fix RayExecutorV2 actor name collision with DP > 1
tomeras91 Apr 20, 2026
8e3c9d6
Merge branch 'main' into fix-ray-v2-dp-instance-id-collision
tomeras91 May 3, 2026
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5 changes: 5 additions & 0 deletions vllm/v1/engine/utils.py
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Original file line number Diff line number Diff line change
Expand Up @@ -403,6 +403,11 @@ def __init__(
range(dp_size), local_dp_ranks, placement_groups
):
dp_vllm_config = copy.deepcopy(vllm_config)
if dp_size > 1:
# Append the DP rank to instance_id so that per-engine
# identifiers (e.g. Ray actor names in RayExecutorV2) are
# unique across DP replicas.
dp_vllm_config.instance_id = f"{dp_vllm_config.instance_id}_dp{index}"
Comment on lines +406 to +410
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@gemini-code-assist gemini-code-assist Bot Apr 20, 2026

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high

The fix correctly addresses the actor name collision for the initial Ray DP startup. However, the same logic appears to be missing in two other critical locations where per-engine configurations are initialized:

  1. Elastic EP Scale-up: In CoreEngineActorManager.scale_up_elastic_ep (around line 766), new engines are launched but their instance_id is not updated with the new DP rank. Additionally, the kv_transfer_config.engine_id update (present in __init__ at line 399) is also missing here. This will cause collisions and incorrect behavior when scaling up a cluster using RayExecutorV2 or KV transfer.
  2. Multiprocessing DP Path: In vllm/v1/engine/core.py::run_engine_core (around line 1083), the vllm_config is modified for kv_transfer_config, but instance_id is not updated. If data_parallel_backend="mp" is used in conjunction with RayExecutorV2, collisions will occur.

To ensure full coverage and consistency, please apply the instance_id update in these locations as well, using the global DP rank (rank and dp_rank respectively). You should also fix the missing kv_transfer_config update in scale_up_elastic_ep.

dp_vllm_config.parallel_config.placement_group = pg
local_client = index < local_engine_count

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