[v1] add callbacks (#10255)

src/llamafactory/v1/utils/callbacks/logging_callback.py

@@ -0,0 +1,64 @@
+# Copyright 2025 the LlamaFactory team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import annotations
+
+import json
+import os
+from typing import TYPE_CHECKING, Any
+
+from .. import logging
+from .trainer_callback import TrainerCallback, TrainerState
+
+
+if TYPE_CHECKING:
+    from ...config import TrainingArguments
+
+
+logger = logging.get_logger(__name__)
+
+
+class LoggingCallback(TrainerCallback):
+    """Logs training metrics to stdout on rank-0 and appends to ``state.log_history``.
+
+    On each logging step the entry is also persisted as a JSON line in
+    ``<output_dir>/trainer_log.jsonl`` so that training history survives crashes.
+    """
+
+    def on_log(
+        self,
+        args: TrainingArguments,
+        state: TrainerState,
+        logs: dict[str, Any],
+        **kwargs: Any,
+    ) -> None:
+        # Persist in history regardless of rank
+        state.log_history.append(dict(logs))
+
+        # Everything below is rank-0 only
+        from ...accelerator.interface import DistributedInterface  # lazy import
+
+        if DistributedInterface().get_rank() != 0:
+            return
+
+        # Human-readable output to stdout
+        display_logs = {**logs, "total_steps": state.num_training_steps}
+        parts = ", ".join(f"{k}: {v:.4f}" if isinstance(v, float) else f"{k}: {v}" for k, v in display_logs.items())
+        logger.info_rank0(parts)
+
+        # Append to JSONL log file in output_dir
+        os.makedirs(args.output_dir, exist_ok=True)
+        log_file = os.path.join(args.output_dir, "trainer_log.jsonl")
+        with open(log_file, "a", encoding="utf-8") as f:
+            f.write(json.dumps(display_logs, ensure_ascii=False) + "\n")