From e70651ac58af6c3446741e8f6b6d4d0d913248c5 Mon Sep 17 00:00:00 2001
From: Meng WANG <49304833+Moenupa@users.noreply.github.com>
Date: Tue, 20 Jan 2026 15:54:07 +0800
Subject: [PATCH] [feat] support `all_exhausted_without_replacement` in
 datasets.interleave_datasets (#10112)

---
 src/llamafactory/data/data_utils.py   | 8 +++++++-
 src/llamafactory/hparams/data_args.py | 4 ++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/llamafactory/data/data_utils.py b/src/llamafactory/data/data_utils.py
index 139425a22..8fcd9554f 100644
--- a/src/llamafactory/data/data_utils.py
+++ b/src/llamafactory/data/data_utils.py
@@ -65,11 +65,17 @@ def merge_dataset(
         if not data_args.streaming:
             logger.warning_rank0_once("We recommend using `mix_strategy=concat` in non-streaming mode.")
 
+        strategy_map: str = {
+            "interleave_under": "first_exhausted",
+            "interleave_over": "all_exhausted",
+            "interleave_once": "all_exhausted_without_replacement",
+        }[data_args.mix_strategy]
+
         return interleave_datasets(
             datasets=all_datasets,
             probabilities=data_args.interleave_probs,
             seed=seed,
-            stopping_strategy="first_exhausted" if data_args.mix_strategy.endswith("under") else "all_exhausted",
+            stopping_strategy=strategy_map,  # type: ignore
         )
 
     else:
diff --git a/src/llamafactory/hparams/data_args.py b/src/llamafactory/hparams/data_args.py
index 921019a02..49d75cf08 100644
--- a/src/llamafactory/hparams/data_args.py
+++ b/src/llamafactory/hparams/data_args.py
@@ -63,9 +63,9 @@ class DataArguments:
         default=16384,
         metadata={"help": "Size of the buffer to randomly sample examples from in dataset streaming."},
     )
-    mix_strategy: Literal["concat", "interleave_under", "interleave_over"] = field(
+    mix_strategy: Literal["concat", "interleave_under", "interleave_over", "interleave_once"] = field(
         default="concat",
-        metadata={"help": "Strategy to use in dataset mixing (concat/interleave) (undersampling/oversampling)."},
+        metadata={"help": "Strategy to use in dataset mixing (concat/interleave) (undersampling/oversampling/sampling w.o. replacement)."},
     )
     interleave_probs: str | None = field(
         default=None,