[Feature] console print statistical metrics (#6339)

* [Feature] console print statistical data

* [Feature] console print statistical data v2 dp_rank

* [Feature] console print statistical data v2 unittest

* [Feature] console print statistical data v3 unittest

tests/engine/test_scheduler_metrics_logger.py

@@ -0,0 +1,74 @@
+"""
+Copyright (c) 2025 PaddlePaddle Authors. All Rights Reserved.
+
+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.
+"""
+
+import types
+from unittest import mock
+
+from fastdeploy.engine.sched.scheduler_metrics_logger import SchedulerMetricsLogger
+
+
+def test_on_decode_tokens_accumulates():
+    logger = SchedulerMetricsLogger(enabled=True, dp_rank=0)
+    logger._decode_tokens_since_last = 0
+
+    logger.on_decode_tokens(3)
+    logger.on_decode_tokens(0)
+    logger.on_decode_tokens(-1)
+
+    assert logger._decode_tokens_since_last == 3
+
+
+def test_log_prefill_batch_logs_expected_message():
+    logger = SchedulerMetricsLogger(enabled=True, dp_rank=2)
+    logger._logger = mock.Mock()
+
+    reqs = [
+        types.SimpleNamespace(prefill_start_index=0, prefill_end_index=4, num_cached_tokens=2),
+        types.SimpleNamespace(prefill_start_index=3, prefill_end_index=3, num_cached_tokens=1),
+    ]
+
+    logger.log_prefill_batch(prefill_reqs=reqs, running_cnt=5, queue_cnt=6, tokens_used=10, token_usage=0.75)
+
+    logger._logger.info.assert_called_once()
+    message = logger._logger.info.call_args[0][0]
+    assert "Prefill batch" in message
+    assert "dp_rank: 2" in message
+    assert "#new-seq: 2" in message
+    assert "#new-token: 4" in message
+    assert "#cached-token: 3" in message
+    assert "token usage: 0.75" in message
+    assert "#running-req: 5" in message
+    assert "#queue-req: 6" in message
+
+
+def test_log_decode_batch_computes_throughput(monkeypatch):
+    logger = SchedulerMetricsLogger(enabled=True, dp_rank=1)
+    logger._logger = mock.Mock()
+    logger._decode_tokens_since_last = 10
+    logger._last_decode_tic = 1.0
+
+    monkeypatch.setattr("fastdeploy.engine.sched.scheduler_metrics_logger.time.perf_counter", lambda: 3.0)
+
+    logger.log_decode_batch(running_cnt=4, queue_cnt=7, tokens_used=8, token_usage=0.5, use_cudagraph=True)
+
+    logger._logger.info.assert_called_once()
+    message = logger._logger.info.call_args[0][0]
+    assert "Decode batch" in message
+    assert "dp_rank: 1" in message
+    assert "gen throughput (token/s): 5.00" in message
+    assert "#queue-req: 7" in message
+    assert logger._decode_tokens_since_last == 0
+    assert logger._last_decode_tic == 3.0