[Misc] correct static type check for GroupCoordinator (#21946)

Signed-off-by: Andy Xie <andy.xning@gmail.com>

vllm/distributed/device_communicators/ray_communicator.py

@@ -70,6 +70,7 @@ class RayPPCommunicator(Communicator):
             assert ray.get_gpu_ids(), "RayPPCommunicator has no GPUs assigned"
 
             self._comm = get_pp_group().device_communicator
+            assert self._comm is not None
 
             # Since we wrap around the vLLM _PP communicator, we use
             # the rank from the vLLM communicator, and ignore the rank

vllm/distributed/eplb/eplb_state.py

@@ -251,6 +251,7 @@ class EplbState:
 
         if global_expert_load is not None:
             ep_group = get_ep_group().device_group
+            assert ep_group is not None
             assert global_expert_load.shape == (model.num_moe_layers,
                                                 model.num_logical_experts)
             assert global_expert_load.dtype == torch.int64
@@ -357,6 +358,7 @@ class EplbState:
 
             # Collect load metrics from all ranks
             ep_group = get_ep_group().device_group
+            assert ep_group is not None
             num_tokens_list = [
                 torch.empty_like(num_tokens) for _ in range(ep_group.size())
             ]
@@ -412,6 +414,7 @@ class EplbState:
         """
 
         ep_group = get_ep_group().device_group
+        assert ep_group is not None
         ep_rank = ep_group.rank()
 
         time_start = None

vllm/distributed/parallel_state.py

@@ -196,10 +196,11 @@ class GroupCoordinator:
     #   3     |   1  |  3   |     1      |       3
     local_rank: int  # local rank used to assign devices
     rank_in_group: int  # rank inside the group
-    cpu_group: ProcessGroup  # group for CPU communication
-    device_group: ProcessGroup  # group for device communication
+    cpu_group: Optional[ProcessGroup]  # group for CPU communication
+    device_group: Optional[ProcessGroup]  # group for device communication
     use_device_communicator: bool  # whether to use device communicator
-    device_communicator: DeviceCommunicatorBase  # device communicator
+    device_communicator: Optional[
+        DeviceCommunicatorBase]  # device communicator
     mq_broadcaster: Optional[Any]  # shared memory broadcaster
 
     def __init__(
@@ -250,7 +251,7 @@ class GroupCoordinator:
 
         self.use_device_communicator = use_device_communicator
 
-        self.device_communicator: DeviceCommunicatorBase = None  # type: ignore
+        self.device_communicator = None
         if use_device_communicator and self.world_size > 1:
             device_comm_cls = resolve_obj_by_qualname(
                 current_platform.get_device_communicator_cls())
@@ -364,6 +365,8 @@ class GroupCoordinator:
             return self._all_reduce_out_place(input_)
 
     def _all_reduce_out_place(self, input_: torch.Tensor) -> torch.Tensor:
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         return self.device_communicator.all_reduce(input_)
 
     def all_gather(self, input_: torch.Tensor, dim: int = -1) -> torch.Tensor:
@@ -384,12 +387,16 @@ class GroupCoordinator:
 
     def _all_gather_out_place(self, input_: torch.Tensor,
                               dim: int) -> torch.Tensor:
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         return self.device_communicator.all_gather(input_, dim)
 
     def all_gatherv(self,
                     input_: Union[torch.Tensor, list[torch.Tensor]],
                     dim: int = 0,
                     sizes: Optional[list[int]] = None):
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         return self.device_communicator.all_gatherv(input_, dim, sizes)
 
     def reduce_scatter(self,
@@ -414,10 +421,14 @@ class GroupCoordinator:
                         input_: torch.Tensor,
                         dim: int = -1,
                         sizes: Optional[list[int]] = None) -> torch.Tensor:
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         return self.device_communicator.reduce_scatterv(input_, dim, sizes)
 
     def _reduce_scatter_out_place(self, input_: torch.Tensor,
                                   dim: int) -> torch.Tensor:
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         return self.device_communicator.reduce_scatter(input_, dim)
 
     def gather(self,
@@ -433,6 +444,8 @@ class GroupCoordinator:
         # Bypass the function if we are using only 1 GPU.
         if world_size == 1:
             return input_
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         return self.device_communicator.gather(input_, dst, dim)
 
     def broadcast(self, input_: torch.Tensor, src: int = 0):
@@ -667,6 +680,8 @@ class GroupCoordinator:
         assert dst < self.world_size, f"Invalid dst rank ({dst})"
 
         if self.use_cpu_custom_send_recv:
+            if self.device_communicator is None:
+                raise ValueError("No device communicator found")
             self.device_communicator.send_tensor_dict(  # type: ignore
                 tensor_dict, dst)
             return None
@@ -727,6 +742,8 @@ class GroupCoordinator:
         assert src < self.world_size, f"Invalid src rank ({src})"
 
         if self.use_cpu_custom_send_recv:
+            if self.device_communicator is None:
+                raise ValueError("No device communicator found")
             return self.device_communicator.recv_tensor_dict(  # type: ignore
                 src)
 
@@ -784,6 +801,8 @@ class GroupCoordinator:
     def send(self, tensor: torch.Tensor, dst: Optional[int] = None) -> None:
         """Sends a tensor to the destination rank in a blocking way"""
         """NOTE: `dst` is the local rank of the destination rank."""
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         self.device_communicator.send(tensor, dst)
 
     def recv(self,
@@ -792,6 +811,8 @@ class GroupCoordinator:
              src: Optional[int] = None) -> torch.Tensor:
         """Receives a tensor from the source rank."""
         """NOTE: `src` is the local rank of the source rank."""
+        if self.device_communicator is None:
+            raise ValueError("No device communicator found")
         return self.device_communicator.recv(size, dtype, src)
 
     def destroy(self):