[RL] Fix illegal memory for _import_static_state (#7733)

Co-authored-by: nanjiangwill <willjiang2018@gmail.com>

python/sglang/srt/managers/scheduler.py

@@ -2346,6 +2346,7 @@ class Scheduler(
             self.stashed_model_static_state = _export_static_state(
                 self.tp_worker.worker.model_runner.model
             )
+            torch.distributed.barrier(self.tp_cpu_group)
             self.memory_saver_adapter.pause(GPU_MEMORY_TYPE_WEIGHTS)
 
         return ReleaseMemoryOccupationReqOutput()
@@ -2357,6 +2358,7 @@ class Scheduler(
 
         if GPU_MEMORY_TYPE_WEIGHTS in tags:
             self.memory_saver_adapter.resume(GPU_MEMORY_TYPE_WEIGHTS)
+            torch.distributed.barrier(self.tp_cpu_group)
             _import_static_state(
                 self.tp_worker.worker.model_runner.model,
                 self.stashed_model_static_state,