.

train_sft_ds.py

@@ -237,6 +237,12 @@ class SFTDataCollator:
         #     raise RuntimeError(f"EMPTY BATCH in collator on rank={os.environ.get('RANK','0')}. "
         #                    f"Check sampler/sharding & make eval size >= world_size * per_device_eval_batch_size.")
         
+        if not features:
+            raise RuntimeError(
+                f"[FATAL][RANK={os.environ.get('RANK','?')}] Empty batch reached collator. "
+                f"Check dataset sharding/streaming."
+            )
+
         def _to_list(x): return x.tolist() if isinstance(x, torch.Tensor) else list(x)
         input_ids   = [_to_list(f["input_ids"])      for f in features]
         attn_masks  = [_to_list(f["attention_mask"]) for f in features]
@@ -269,11 +275,11 @@ class SFTDataCollator:
                 flush=True
             )
         # 额外严苛校验：防止空 batch 继续往下走
-        if not features:
-            raise RuntimeError(
-                f"[FATAL][RANK={os.environ.get('RANK','?')}] Empty batch reached collator. "
-                f"Check dataset sharding/streaming."
-            )
+        # if not features:
+        #     raise RuntimeError(
+        #         f"[FATAL][RANK={os.environ.get('RANK','?')}] Empty batch reached collator. "
+        #         f"Check dataset sharding/streaming."
+        #     )
         # >>> DEBUG END
 
         return {
@@ -459,13 +465,6 @@ def main():
                     yield ex
         train_stream = QwenChatSFTDataset(ex_iter2(), tokenizer, seq_len=args.seq_len)
 
-    def has_one_sample(stream):
-        it = iter(stream)
-        try:
-            next(it); return 1
-        except StopIteration:
-            return 0
-        
     # ====== 一致性探针（与上面保持同逻辑）=====
     ds_stream_probe2 = load_dataset("json", data_files={"train": files}, split="train", streaming=True)
     if world_size > 1 and len(files) >= world_size:
@@ -478,24 +477,55 @@ def main():
                     yield ex
         probe_stream = QwenChatSFTDataset(ex_iter2_probe(), tokenizer, seq_len=args.seq_len)
 
+    def has_at_least(stream, n: int):
+        it = iter(stream)
+        for _ in range(n):
+            try:
+                next(it)
+            except StopIteration:
+                return 0
+        return 1
 
-    local_ok = has_one_sample(probe_stream)
+    need = max(1, args.gradient_accumulation_steps)
+
+    local_ok = has_at_least(probe_stream, need)
 
     if dist.is_available() and dist.is_initialized():
-        # t = torch.tensor(local_ok, device=("cuda" if torch.cuda.is_available() else "cpu"))
-        t = torch.tensor(
-            local_ok,
-            device=(f"cuda:{local_rank}" if torch.cuda.is_available() and local_rank >= 0 else "cpu")
-        )
+        t = torch.tensor(local_ok, device=(f"cuda:{local_rank}" if torch.cuda.is_available() and local_rank >= 0 else "cpu"))
         dist.all_reduce(t, op=dist.ReduceOp.MIN)
         if t.item() == 0:
             if is_main_process():
-                print("[FATAL] 至少有一个 rank 没有任何样本。请减少 WORLD_SIZE 或修正分片；本次训练不会启动。", flush=True)
+                print(
+                    f"[FATAL] 至少有一个 rank 在一个优化 step 内供不上 {need} 个微批 (GA={need})。 "
+                    f"请减少 GA 或扩大/清洗数据；本次训练不会启动。",
+                    flush=True
+                )
             dist.barrier()
             sys.exit(2)
     else:
         if local_ok == 0:
-            print("[FATAL] 本机无样本，退出。", flush=True); sys.exit(2)
+            print(
+                f"[FATAL] 本机在一个优化 step 内供不上 {need} 个微批 (GA={need})。 "
+                f"请减少 GA 或扩大/清洗数据；本次训练不会启动。",
+                flush=True
+            )
+            sys.exit(2)
+
+    # if dist.is_available() and dist.is_initialized():
+    #     # t = torch.tensor(local_ok, device=("cuda" if torch.cuda.is_available() else "cpu"))
+    #     t = torch.tensor(
+    #         local_ok,
+    #         device=(f"cuda:{local_rank}" if torch.cuda.is_available() and local_rank >= 0 else "cpu")
+    #     )
+    #     dist.all_reduce(t, op=dist.ReduceOp.MIN)
+    #     if t.item() == 0:
+    #         if is_main_process():
+    #             print("[FATAL] 至少有一个 rank 没有任何样本。请减少 WORLD_SIZE 或修正分片；本次训练不会启动。", flush=True)
+    #         dist.barrier()
+    #         sys.exit(2)
+    # else:
+    #     if local_ok == 0:
+    #         print("[FATAL] 本机无样本，退出。", flush=True); sys.exit(2)
 
     # ---- Eval 构造：优先使用 --eval_data_glob；否则才用 eval_ratio 抽样 ----
     eval_dataset: Optional[Dataset] = None
@@ -552,9 +582,9 @@ def main():
 
         r = len(eval_dataset) % global_bs
         if r != 0:
-            need = global_bs - r
-            # 你的 eval_dataset 是上面自定义的 ListDataset，带 .items
-            eval_dataset.items += eval_dataset.items[:need]
+            pad_need = global_bs - r
+            eval_dataset.items += eval_dataset.items[:pad_need]
+
             if is_main_process():
                 print(f"[eval] padded eval set to {len(eval_dataset)} "
                     f"(world_size={ws}, per_device_eval_batch_size={be}, global_bs={global_bs})",