Support multi-node DP attention (#2925)

Co-authored-by: dhou-xai <dhou@x.ai>

python/sglang/srt/managers/schedule_batch.py

@@ -1003,6 +1003,11 @@ class ScheduleBatch:
         self.req_pool_indices = torch.empty(0, dtype=torch.int32, device=self.device)
         self.seq_lens_sum = 0
         self.extend_num_tokens = 0
+        self.sampling_info = SamplingBatchInfo.from_schedule_batch(
+            self,
+            self.model_config.vocab_size,
+            enable_overlap_schedule=self.enable_overlap,
+        )
 
     def prepare_for_decode(self):
         self.forward_mode = ForwardMode.DECODE
@@ -1117,7 +1122,7 @@ class ScheduleBatch:
             self.spec_info.merge_batch(other.spec_info)
 
     def get_model_worker_batch(self):
-        if self.forward_mode.is_decode() or self.forward_mode.is_idle():
+        if self.forward_mode.is_decode_or_idle():
             extend_seq_lens = extend_prefix_lens = extend_logprob_start_lens = None
         else:
             extend_seq_lens = self.extend_lens