Patch PyTorch's bug that cross-process tensor transfer will lead to wrong device (#4565)

python/sglang/srt/entrypoints/verl_engine.py

@@ -19,6 +19,7 @@ import torch.distributed as dist
 from torch.distributed.tensor import DeviceMesh, DTensor
 
 from sglang.srt.model_executor.model_runner import LocalSerializedTensor
+from sglang.srt.patch_torch import monkey_patch_torch_reductions
 from sglang.srt.server import Engine
 from sglang.srt.utils import MultiprocessingSerializer, broadcast_pyobj
 
@@ -30,6 +31,7 @@ class VerlEngine:
         nnodes: int = 1,
         **kwargs,
     ):
+        monkey_patch_torch_reductions()
         self._device_mesh_cpu = device_mesh_cpu
         self._tp_rank = device_mesh_cpu.get_local_rank()
         self._tp_size = device_mesh_cpu.size()