Run qwen3-4b example hangs on actor model update_weights

When I use official case run qwen3-4b rl example(https://github.com/THUDM/slime/blob/main/scripts/run-qwen3-4B.sh), found the following issues on update weights:
pdate weights: 6%|▋ | 1/16 [11:01<2:45:20, 661.36s/it]
Traceback (most recent call last):
File "/root/slime/train.py", line 119, in
train(args)
File "/root/slime/train.py", line 34, in train
actor_model.update_weights()
File "/root/slime/slime/ray/actor_group.py", line 124, in update_weights
return ray.get([actor.update_weights.remote() for actor in self._actor_handlers])
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/ray/_private/auto_init_hook.py", line 22, in auto_init_wrapper
return fn(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/ray/_private/client_mode_hook.py", line 104, in wrapper
return func(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/ray/_private/worker.py", line 2882, in get
values, debugger_breakpoint = worker.get_objects(object_refs, timeout=timeout)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/usr/local/lib/python3.12/site-packages/ray/_private/worker.py", line 970, in get_objects
raise value
ray.exceptions.ActorUnavailableError: The actor 480ce8b4cb84b1cb6a0b66ba02000000 is unavailable: The actor is temporarily unavailable: RpcError: RPC Error message: Socket closed; RPC Error details: rpc_code: 14. The task may or may not have been executed on the actor.

I use sglang 0.5.5 and slime commit f47796226cf6d8e5810c6630e4214634c80aae0a

Reproduce the failure with scripts/run-qwen3-4B.sh using the reported slime commit and sglang 0.5.5. Inspect train.py:34 and slime/ray/actor_group.py:124 around actor_model.update_weights(), then trace the unavailable actor; done means the example completes weight updates without ActorUnavailableError.