[DP] Fix Prometheus Logging (#21257)

Signed-off-by: Robert Shaw <robshaw@redhat.com>
Co-authored-by: Robert Shaw <robshaw@redhat.com>

tests/v1/engine/test_async_llm.py

@@ -336,9 +336,10 @@ async def test_customize_loggers(monkeypatch):
 
         await engine.do_log_stats()
 
-        assert len(engine.stat_loggers) == 1
-        assert len(engine.stat_loggers[0]) == 1
-        engine.stat_loggers[0][0].log.assert_called_once()
+        stat_loggers = engine.logger_manager.per_engine_logger_dict
+        assert len(stat_loggers) == 1
+        assert len(stat_loggers[0]) == 1
+        stat_loggers[0][0].log.assert_called_once()
 
 
 @pytest.mark.asyncio(scope="module")

tests/v1/test_async_llm_dp.py

@@ -90,8 +90,10 @@ async def test_load(output_kind: RequestOutputKind,
         def __init__(self, vllm_config: VllmConfig, engine_index: int = 0):
             stats_loggers[engine_index] = self
 
-        def record(self, scheduler_stats: Optional[SchedulerStats],
-                   iteration_stats: Optional[IterationStats]):
+        def record(self,
+                   scheduler_stats: Optional[SchedulerStats],
+                   iteration_stats: Optional[IterationStats],
+                   engine_idx: int = 0):
             if iteration_stats:
                 self.finished_req_count += len(
                     iteration_stats.finished_requests)

vllm/v1/engine/async_llm.py

@@ -36,10 +36,9 @@ from vllm.v1.engine.output_processor import (OutputProcessor,
 from vllm.v1.engine.parallel_sampling import ParentRequest
 from vllm.v1.engine.processor import Processor
 from vllm.v1.executor.abstract import Executor
-from vllm.v1.metrics.loggers import (StatLoggerBase, StatLoggerFactory,
-                                     setup_default_loggers)
+from vllm.v1.metrics.loggers import StatLoggerFactory, StatLoggerManager
 from vllm.v1.metrics.prometheus import shutdown_prometheus
-from vllm.v1.metrics.stats import IterationStats, SchedulerStats
+from vllm.v1.metrics.stats import IterationStats
 
 logger = init_logger(__name__)
 
@@ -95,14 +94,6 @@ class AsyncLLM(EngineClient):
         self.log_requests = log_requests
         self.log_stats = log_stats
 
-        # Set up stat loggers; independent set for each DP rank.
-        self.stat_loggers: list[list[StatLoggerBase]] = setup_default_loggers(
-            vllm_config=vllm_config,
-            log_stats=self.log_stats,
-            engine_num=vllm_config.parallel_config.data_parallel_size,
-            custom_stat_loggers=stat_loggers,
-        )
-
         # Tokenizer (+ ensure liveness if running in another process).
         self.tokenizer = init_tokenizer_from_configs(
             model_config=vllm_config.model_config,
@@ -121,7 +112,6 @@ class AsyncLLM(EngineClient):
                                                 log_stats=self.log_stats)
 
         # EngineCore (starts the engine in background process).
-
         self.engine_core = EngineCoreClient.make_async_mp_client(
             vllm_config=vllm_config,
             executor_class=executor_class,
@@ -129,9 +119,17 @@ class AsyncLLM(EngineClient):
             client_addresses=client_addresses,
             client_index=client_index,
         )
-        if self.stat_loggers:
-            for stat_logger in self.stat_loggers[0]:
-                stat_logger.log_engine_initialized()
+
+        # Loggers.
+        self.logger_manager: Optional[StatLoggerManager] = None
+        if self.log_stats:
+            self.logger_manager = StatLoggerManager(
+                vllm_config=vllm_config,
+                engine_idxs=self.engine_core.engine_ranks,
+                custom_stat_loggers=stat_loggers,
+            )
+            self.logger_manager.log_engine_initialized()
+
         self.output_handler: Optional[asyncio.Task] = None
         try:
             # Start output handler eagerly if we are in the asyncio eventloop.
@@ -370,7 +368,7 @@ class AsyncLLM(EngineClient):
         engine_core = self.engine_core
         output_processor = self.output_processor
         log_stats = self.log_stats
-        stat_loggers = self.stat_loggers if log_stats else None
+        logger_manager = self.logger_manager
 
         async def output_handler():
             try:
@@ -410,9 +408,9 @@ class AsyncLLM(EngineClient):
                     # 4) Logging.
                     # TODO(rob): make into a coroutine and launch it in
                     # background thread once Prometheus overhead is non-trivial.
-                    if stat_loggers:
-                        AsyncLLM._record_stats(
-                            stat_loggers[outputs.engine_index],
+                    if logger_manager:
+                        logger_manager.record(
+                            engine_idx=outputs.engine_index,
                             scheduler_stats=outputs.scheduler_stats,
                             iteration_stats=iteration_stats,
                         )
@@ -431,18 +429,6 @@ class AsyncLLM(EngineClient):
         if self.log_requests:
             logger.info("Aborted request %s.", request_id)
 
-    @staticmethod
-    def _record_stats(
-        stat_loggers: list[StatLoggerBase],
-        scheduler_stats: Optional[SchedulerStats],
-        iteration_stats: Optional[IterationStats],
-    ):
-        """static so that it can be used from the output_handler task
-        without a circular ref to AsyncLLM."""
-        for stat_logger in stat_loggers:
-            stat_logger.record(scheduler_stats=scheduler_stats,
-                               iteration_stats=iteration_stats)
-
     async def encode(
         self,
         prompt: PromptType,
@@ -547,9 +533,8 @@ class AsyncLLM(EngineClient):
         scheduler_outputs=None,
         model_output=None,
     ) -> None:
-        for loggers in self.stat_loggers:
-            for stat_logger in loggers:
-                stat_logger.log()
+        if self.logger_manager:
+            self.logger_manager.log()
 
     async def check_health(self) -> None:
         logger.debug("Called check_health.")
@@ -653,18 +638,16 @@ class AsyncLLM(EngineClient):
             new_data_parallel_size
 
         # recreate stat loggers
-        if new_data_parallel_size > old_data_parallel_size:
-            stat_loggers: list[list[StatLoggerBase]] = setup_default_loggers(
+        if new_data_parallel_size > old_data_parallel_size and self.log_stats:
+            # TODO(rob): fix this after talking with Ray team.
+            # This resets all the prometheus metrics since we
+            # unregister during initialization. Need to understand
+            # the intended behavior here better.
+            self.logger_manager = StatLoggerManager(
                 vllm_config=self.vllm_config,
-                log_stats=self.log_stats,
-                engine_num=new_data_parallel_size,
+                engine_idxs=list(range(new_data_parallel_size)),
                 custom_stat_loggers=None,
             )
-            num_new_engines = len(stat_loggers) - len(self.stat_loggers)
-            self.stat_loggers.extend(stat_loggers[-num_new_engines:])
-        else:
-            for _ in range(old_data_parallel_size - new_data_parallel_size):
-                self.stat_loggers.pop()
 
     @property
     def is_running(self) -> bool:

vllm/v1/engine/core_client.py

@@ -432,14 +432,15 @@ class MPClient(EngineCoreClient):
             external_dp_lb = parallel_config.data_parallel_external_lb
 
             offline_mode = parallel_config.data_parallel_rank_local is not None
-            engine_ranks = [dp_rank] if (offline_mode
-                                         or external_dp_lb) else range(dp_size)
+            self.engine_ranks = ([dp_rank] if
+                                 (offline_mode or external_dp_lb) else list(
+                                     range(dp_size)))
             assert parallel_config.data_parallel_size_local <= len(
-                engine_ranks)
+                self.engine_ranks)
 
             # ZMQ identity of each engine that this client will talk to.
             self.core_engines: list[EngineIdentity] = [
-                index.to_bytes(2, "little") for index in engine_ranks
+                index.to_bytes(2, "little") for index in self.engine_ranks
             ]
 
             # Wait for ready messages from each engine on the input socket.

vllm/v1/metrics/loggers.py

@@ -4,7 +4,7 @@
 import logging
 import time
 from abc import ABC, abstractmethod
-from typing import Callable, Optional
+from typing import Callable, Optional, Union
 
 import numpy as np
 import prometheus_client
@@ -35,8 +35,10 @@ class StatLoggerBase(ABC):
         ...
 
     @abstractmethod
-    def record(self, scheduler_stats: Optional[SchedulerStats],
-               iteration_stats: Optional[IterationStats]):
+    def record(self,
+               scheduler_stats: Optional[SchedulerStats],
+               iteration_stats: Optional[IterationStats],
+               engine_idx: int = 0):
         ...
 
     @abstractmethod
@@ -78,8 +80,10 @@ class LoggingStatLogger(StatLoggerBase):
         # Compute summary metrics for tracked stats
         return float(np.sum(tracked_stats) / (now - self.last_log_time))
 
-    def record(self, scheduler_stats: Optional[SchedulerStats],
-               iteration_stats: Optional[IterationStats]):
+    def record(self,
+               scheduler_stats: Optional[SchedulerStats],
+               iteration_stats: Optional[IterationStats],
+               engine_idx: int = 0):
         """Log Stats to standard output."""
 
         if iteration_stats:
@@ -146,233 +150,290 @@ class PrometheusStatLogger(StatLoggerBase):
     _histogram_cls = prometheus_client.Histogram
     _spec_decoding_cls = SpecDecodingProm
 
-    def __init__(self, vllm_config: VllmConfig, engine_index: int = 0):
+    def __init__(self,
+                 vllm_config: VllmConfig,
+                 engine_indexes: Optional[list[int]] = None):
+        if engine_indexes is None:
+            engine_indexes = [0]
+        self.engine_indexes = engine_indexes
 
         unregister_vllm_metrics()
         self.vllm_config = vllm_config
-        self.engine_index = engine_index
         # Use this flag to hide metrics that were deprecated in
         # a previous release and which will be removed future
         self.show_hidden_metrics = \
             vllm_config.observability_config.show_hidden_metrics
 
         labelnames = ["model_name", "engine"]
-        labelvalues = [
-            vllm_config.model_config.served_model_name,
-            str(engine_index)
-        ]
-
+        model_name = vllm_config.model_config.served_model_name
         max_model_len = vllm_config.model_config.max_model_len
 
+        if (len(self.engine_indexes) > 1
+                and vllm_config.speculative_config is not None):
+            raise NotImplementedError("Prometheus metrics with Spec Decoding "
+                                      "with >1 EngineCore per AsyncLLM is not "
+                                      "supported yet.")
+        spec_decode_labelvalues = [
+            vllm_config.model_config.served_model_name,
+            str(self.engine_indexes[0])
+        ]
         self.spec_decoding_prom = self._spec_decoding_cls(
-            vllm_config.speculative_config, labelnames, labelvalues)
+            vllm_config.speculative_config, labelnames,
+            spec_decode_labelvalues)
 
         #
         # Scheduler state
         #
-        self.gauge_scheduler_running = self._gauge_cls(
+        gauge_scheduler_running = self._gauge_cls(
             name="vllm:num_requests_running",
             documentation="Number of requests in model execution batches.",
             multiprocess_mode="mostrecent",
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.gauge_scheduler_running = make_per_engine(gauge_scheduler_running,
+                                                       engine_indexes,
+                                                       model_name)
 
-        self.gauge_scheduler_waiting = self._gauge_cls(
+        gauge_scheduler_waiting = self._gauge_cls(
             name="vllm:num_requests_waiting",
             documentation="Number of requests waiting to be processed.",
             multiprocess_mode="mostrecent",
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.gauge_scheduler_waiting = make_per_engine(gauge_scheduler_waiting,
+                                                       engine_indexes,
+                                                       model_name)
 
         #
         # GPU cache
         #
         # Deprecated in 0.9 - Renamed as vllm:kv_cache_usage_perc
         # TODO: in 0.10, only enable if show_hidden_metrics=True
-        self.gauge_gpu_cache_usage = self._gauge_cls(
+        gauge_gpu_cache_usage = self._gauge_cls(
             name="vllm:gpu_cache_usage_perc",
             documentation=(
                 "GPU KV-cache usage. 1 means 100 percent usage."
                 "DEPRECATED: Use vllm:kv_cache_usage_perc instead."),
             multiprocess_mode="mostrecent",
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.gauge_gpu_cache_usage = make_per_engine(gauge_gpu_cache_usage,
+                                                     engine_indexes,
+                                                     model_name)
 
         # Deprecated in 0.9 - Renamed as vllm:prefix_cache_queries
         # TODO: in 0.10, only enable if show_hidden_metrics=True
-        self.counter_gpu_prefix_cache_queries = self._counter_cls(
+        counter_gpu_prefix_cache_queries = self._counter_cls(
             name="vllm:gpu_prefix_cache_queries",
-            documentation=
-            ("GPU prefix cache queries, in terms of number of queried tokens."
-             "DEPRECATED: Use vllm:prefix_cache_queries instead."),
-            labelnames=labelnames).labels(*labelvalues)
+            documentation=(
+                "GPU prefix cache queries, in terms of number of queried"
+                "tokens. DEPRECATED: Use vllm:prefix_cache_queries instead."),
+            labelnames=labelnames)
+        self.counter_gpu_prefix_cache_queries = make_per_engine(
+            counter_gpu_prefix_cache_queries, engine_indexes, model_name)
 
         # Deprecated in 0.9 - Renamed as vllm:prefix_cache_hits
         # TODO: in 0.10, only enable if show_hidden_metrics=True
-        self.counter_gpu_prefix_cache_hits = self._counter_cls(
+        counter_gpu_prefix_cache_hits = self._counter_cls(
             name="vllm:gpu_prefix_cache_hits",
             documentation=(
-                "GPU prefix cache hits, in terms of number of cached tokens."
-                "DEPRECATED: Use vllm:prefix_cache_hits instead."),
-            labelnames=labelnames).labels(*labelvalues)
+                "GPU prefix cache hits, in terms of number of cached "
+                "tokens. DEPRECATED: Use vllm:prefix_cache_hits instead."),
+            labelnames=labelnames)
+        self.counter_gpu_prefix_cache_hits = make_per_engine(
+            counter_gpu_prefix_cache_hits, engine_indexes, model_name)
 
-        self.gauge_kv_cache_usage = self._gauge_cls(
+        gauge_kv_cache_usage = self._gauge_cls(
             name="vllm:kv_cache_usage_perc",
             documentation="KV-cache usage. 1 means 100 percent usage.",
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.gauge_kv_cache_usage = make_per_engine(gauge_kv_cache_usage,
+                                                    engine_indexes, model_name)
 
-        self.counter_prefix_cache_queries = self._counter_cls(
+        counter_prefix_cache_queries = self._counter_cls(
             name="vllm:prefix_cache_queries",
             documentation=(
                 "Prefix cache queries, in terms of number of queried tokens."),
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.counter_prefix_cache_queries = make_per_engine(
+            counter_prefix_cache_queries, engine_indexes, model_name)
 
-        self.counter_prefix_cache_hits = self._counter_cls(
+        counter_prefix_cache_hits = self._counter_cls(
             name="vllm:prefix_cache_hits",
             documentation=(
                 "Prefix cache hits, in terms of number of cached tokens."),
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.counter_prefix_cache_hits = make_per_engine(
+            counter_prefix_cache_hits, engine_indexes, model_name)
 
         #
         # Counters
         #
-        self.counter_num_preempted_reqs = self._counter_cls(
+        counter_num_preempted_reqs = self._counter_cls(
             name="vllm:num_preemptions",
             documentation="Cumulative number of preemption from the engine.",
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.counter_num_preempted_reqs = make_per_engine(
+            counter_num_preempted_reqs, engine_indexes, model_name)
 
-        self.counter_prompt_tokens = self._counter_cls(
+        counter_prompt_tokens = self._counter_cls(
             name="vllm:prompt_tokens",
             documentation="Number of prefill tokens processed.",
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.counter_prompt_tokens = make_per_engine(counter_prompt_tokens,
+                                                     engine_indexes,
+                                                     model_name)
 
-        self.counter_generation_tokens = self._counter_cls(
+        counter_generation_tokens = self._counter_cls(
             name="vllm:generation_tokens",
             documentation="Number of generation tokens processed.",
-            labelnames=labelnames).labels(*labelvalues)
+            labelnames=labelnames)
+        self.counter_generation_tokens = make_per_engine(
+            counter_generation_tokens, engine_indexes, model_name)
 
-        self.counter_request_success: dict[FinishReason,
-                                           prometheus_client.Counter] = {}
+        self.counter_request_success: dict[FinishReason, dict[
+            int, prometheus_client.Counter]] = {}
         counter_request_success_base = self._counter_cls(
             name="vllm:request_success",
             documentation="Count of successfully processed requests.",
             labelnames=labelnames + ["finished_reason"])
         for reason in FinishReason:
-            self.counter_request_success[
-                reason] = counter_request_success_base.labels(*(labelvalues +
-                                                                [str(reason)]))
+            self.counter_request_success[reason] = {
+                idx:
+                counter_request_success_base.labels(model_name, str(idx),
+                                                    str(reason))
+                for idx in engine_indexes
+            }
 
         #
         # Histograms of counts
         #
-        self.histogram_num_prompt_tokens_request = \
-            self._histogram_cls(
-                name="vllm:request_prompt_tokens",
-                documentation="Number of prefill tokens processed.",
-                buckets=build_1_2_5_buckets(max_model_len),
-                labelnames=labelnames).labels(*labelvalues)
-
-        self.histogram_num_generation_tokens_request = \
-            self._histogram_cls(
-                name="vllm:request_generation_tokens",
-                documentation="Number of generation tokens processed.",
-                buckets=build_1_2_5_buckets(max_model_len),
-                labelnames=labelnames).labels(*labelvalues)
+        histogram_num_prompt_tokens_request = self._histogram_cls(
+            name="vllm:request_prompt_tokens",
+            documentation="Number of prefill tokens processed.",
+            buckets=build_1_2_5_buckets(max_model_len),
+            labelnames=labelnames)
+        self.histogram_num_prompt_tokens_request = make_per_engine(
+            histogram_num_prompt_tokens_request, engine_indexes, model_name)
+
+        histogram_num_generation_tokens_request = self._histogram_cls(
+            name="vllm:request_generation_tokens",
+            documentation="Number of generation tokens processed.",
+            buckets=build_1_2_5_buckets(max_model_len),
+            labelnames=labelnames)
+        self.histogram_num_generation_tokens_request = make_per_engine(
+            histogram_num_generation_tokens_request, engine_indexes,
+            model_name)
 
         # TODO: This metric might be incorrect in case of using multiple
         # api_server counts which uses prometheus mp.
         # See: https://github.com/vllm-project/vllm/pull/18053
-        self.histogram_iteration_tokens = \
-            self._histogram_cls(
-                name="vllm:iteration_tokens_total",
-                documentation="Histogram of number of tokens per engine_step.",
-                buckets=[
-                    1, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192,
-                    16384
-                ],
-                labelnames=labelnames).labels(*labelvalues)
-
-        self.histogram_max_num_generation_tokens_request = \
-            self._histogram_cls(
-                name="vllm:request_max_num_generation_tokens",
-                documentation=
-                "Histogram of maximum number of requested generation tokens.",
-                buckets=build_1_2_5_buckets(max_model_len),
-                labelnames=labelnames).labels(*labelvalues)
-
-        self.histogram_n_request = \
-            self._histogram_cls(
-                name="vllm:request_params_n",
-                documentation="Histogram of the n request parameter.",
-                buckets=[1, 2, 5, 10, 20],
-                labelnames=labelnames).labels(*labelvalues)
-
-        self.histogram_max_tokens_request = \
-            self._histogram_cls(
-                name="vllm:request_params_max_tokens",
-                documentation="Histogram of the max_tokens request parameter.",
-                buckets=build_1_2_5_buckets(max_model_len),
-                labelnames=labelnames).labels(*labelvalues)
+        histogram_iteration_tokens = self._histogram_cls(
+            name="vllm:iteration_tokens_total",
+            documentation="Histogram of number of tokens per engine_step.",
+            buckets=[
+                1, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384
+            ],
+            labelnames=labelnames)
+        self.histogram_iteration_tokens = make_per_engine(
+            histogram_iteration_tokens, engine_indexes, model_name)
+
+        histogram_max_num_generation_tokens_request = self._histogram_cls(
+            name="vllm:request_max_num_generation_tokens",
+            documentation=
+            "Histogram of maximum number of requested generation tokens.",
+            buckets=build_1_2_5_buckets(max_model_len),
+            labelnames=labelnames)
+        self.histogram_max_num_generation_tokens_request = make_per_engine(
+            histogram_max_num_generation_tokens_request, engine_indexes,
+            model_name)
+
+        histogram_n_request = self._histogram_cls(
+            name="vllm:request_params_n",
+            documentation="Histogram of the n request parameter.",
+            buckets=[1, 2, 5, 10, 20],
+            labelnames=labelnames)
+        self.histogram_n_request = make_per_engine(histogram_n_request,
+                                                   engine_indexes, model_name)
+
+        histogram_max_tokens_request = self._histogram_cls(
+            name="vllm:request_params_max_tokens",
+            documentation="Histogram of the max_tokens request parameter.",
+            buckets=build_1_2_5_buckets(max_model_len),
+            labelnames=labelnames)
+        self.histogram_max_tokens_request = make_per_engine(
+            histogram_max_tokens_request, engine_indexes, model_name)
 
         #
         # Histogram of timing intervals
         #
-        self.histogram_time_to_first_token = \
-            self._histogram_cls(
-                name="vllm:time_to_first_token_seconds",
-                documentation="Histogram of time to first token in seconds.",
-                buckets=[
-                    0.001, 0.005, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.25, 0.5,
-                    0.75, 1.0, 2.5, 5.0, 7.5, 10.0, 20.0, 40.0, 80.0, 160.0,
-                    640.0, 2560.0
-                ],
-                labelnames=labelnames).labels(*labelvalues)
-
-        self.histogram_time_per_output_token = \
-            self._histogram_cls(
-                name="vllm:time_per_output_token_seconds",
-                documentation="Histogram of time per output token in seconds.",
-                buckets=[
-                    0.01, 0.025, 0.05, 0.075, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5,
-                    0.75, 1.0, 2.5, 5.0, 7.5, 10.0, 20.0, 40.0, 80.0
-                ],
-                labelnames=labelnames).labels(*labelvalues)
+        histogram_time_to_first_token = self._histogram_cls(
+            name="vllm:time_to_first_token_seconds",
+            documentation="Histogram of time to first token in seconds.",
+            buckets=[
+                0.001, 0.005, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.25, 0.5,
+                0.75, 1.0, 2.5, 5.0, 7.5, 10.0, 20.0, 40.0, 80.0, 160.0, 640.0,
+                2560.0
+            ],
+            labelnames=labelnames)
+        self.histogram_time_to_first_token = make_per_engine(
+            histogram_time_to_first_token, engine_indexes, model_name)
+
+        histogram_time_per_output_token = self._histogram_cls(
+            name="vllm:time_per_output_token_seconds",
+            documentation="Histogram of time per output token in seconds.",
+            buckets=[
+                0.01, 0.025, 0.05, 0.075, 0.1, 0.15, 0.2, 0.3, 0.4, 0.5, 0.75,
+                1.0, 2.5, 5.0, 7.5, 10.0, 20.0, 40.0, 80.0
+            ],
+            labelnames=labelnames)
+        self.histogram_time_per_output_token = make_per_engine(
+            histogram_time_per_output_token, engine_indexes, model_name)
 
         request_latency_buckets = [
             0.3, 0.5, 0.8, 1.0, 1.5, 2.0, 2.5, 5.0, 10.0, 15.0, 20.0, 30.0,
             40.0, 50.0, 60.0, 120.0, 240.0, 480.0, 960.0, 1920.0, 7680.0
         ]
-        self.histogram_e2e_time_request = \
-            self._histogram_cls(
-                name="vllm:e2e_request_latency_seconds",
-                documentation="Histogram of e2e request latency in seconds.",
-                buckets=request_latency_buckets,
-                labelnames=labelnames).labels(*labelvalues)
-        self.histogram_queue_time_request = \
-            self._histogram_cls(
-                name="vllm:request_queue_time_seconds",
-                documentation=
-                "Histogram of time spent in WAITING phase for request.",
-                buckets=request_latency_buckets,
-                labelnames=labelnames).labels(*labelvalues)
-        self.histogram_inference_time_request = \
-            self._histogram_cls(
-                name="vllm:request_inference_time_seconds",
-                documentation=
-                "Histogram of time spent in RUNNING phase for request.",
-                buckets=request_latency_buckets,
-                labelnames=labelnames).labels(*labelvalues)
-        self.histogram_prefill_time_request = \
-            self._histogram_cls(
-                name="vllm:request_prefill_time_seconds",
-                documentation=
-                "Histogram of time spent in PREFILL phase for request.",
-                buckets=request_latency_buckets,
-                labelnames=labelnames).labels(*labelvalues)
-        self.histogram_decode_time_request = \
-            self._histogram_cls(
-                name="vllm:request_decode_time_seconds",
-                documentation=
-                "Histogram of time spent in DECODE phase for request.",
-                buckets=request_latency_buckets,
-                labelnames=labelnames).labels(*labelvalues)
+        histogram_e2e_time_request = self._histogram_cls(
+            name="vllm:e2e_request_latency_seconds",
+            documentation="Histogram of e2e request latency in seconds.",
+            buckets=request_latency_buckets,
+            labelnames=labelnames)
+        self.histogram_e2e_time_request = make_per_engine(
+            histogram_e2e_time_request, engine_indexes, model_name)
+
+        histogram_queue_time_request = self._histogram_cls(
+            name="vllm:request_queue_time_seconds",
+            documentation=
+            "Histogram of time spent in WAITING phase for request.",
+            buckets=request_latency_buckets,
+            labelnames=labelnames)
+        self.histogram_queue_time_request = make_per_engine(
+            histogram_queue_time_request, engine_indexes, model_name)
+
+        histogram_inference_time_request = self._histogram_cls(
+            name="vllm:request_inference_time_seconds",
+            documentation=
+            "Histogram of time spent in RUNNING phase for request.",
+            buckets=request_latency_buckets,
+            labelnames=labelnames)
+        self.histogram_inference_time_request = make_per_engine(
+            histogram_inference_time_request, engine_indexes, model_name)
+
+        histogram_prefill_time_request = self._histogram_cls(
+            name="vllm:request_prefill_time_seconds",
+            documentation=
+            "Histogram of time spent in PREFILL phase for request.",
+            buckets=request_latency_buckets,
+            labelnames=labelnames)
+        self.histogram_prefill_time_request = make_per_engine(
+            histogram_prefill_time_request, engine_indexes, model_name)
+
+        histogram_decode_time_request = self._histogram_cls(
+            name="vllm:request_decode_time_seconds",
+            documentation=
+            "Histogram of time spent in DECODE phase for request.",
+            buckets=request_latency_buckets,
+            labelnames=labelnames)
+        self.histogram_decode_time_request = make_per_engine(
+            histogram_decode_time_request, engine_indexes, model_name)
 
         #
         # LoRA metrics
@@ -382,6 +443,9 @@ class PrometheusStatLogger(StatLoggerBase):
         # api_server counts which uses prometheus mp.
         self.gauge_lora_info: Optional[prometheus_client.Gauge] = None
         if vllm_config.lora_config is not None:
+            if len(self.engine_indexes) > 1:
+                raise NotImplementedError(
+                    "LoRA in DP mode is not supported yet.")
             self.labelname_max_lora = "max_lora"
             self.labelname_waiting_lora_adapters = "waiting_lora_adapters"
             self.labelname_running_lora_adapters = "running_lora_adapters"
@@ -399,9 +463,8 @@ class PrometheusStatLogger(StatLoggerBase):
                 )
 
     def log_metrics_info(self, type: str, config_obj: SupportsMetricsInfo):
-
         metrics_info = config_obj.metrics_info()
-        metrics_info["engine"] = self.engine_index
+        metrics_info["engine"] = ""
 
         name, documentation = None, None
         if type == "cache_config":
@@ -417,27 +480,36 @@ class PrometheusStatLogger(StatLoggerBase):
             documentation=documentation,
             multiprocess_mode="mostrecent",
             labelnames=metrics_info.keys(),
-        ).labels(**metrics_info)
-        info_gauge.set(1)
-
-    def record(self, scheduler_stats: Optional[SchedulerStats],
-               iteration_stats: Optional[IterationStats]):
+        )
+        for engine_index in self.engine_indexes:
+            metrics_info = config_obj.metrics_info()
+            metrics_info["engine"] = str(engine_index)
+            info_gauge.labels(**metrics_info).set(1)
+
+    def record(self,
+               scheduler_stats: Optional[SchedulerStats],
+               iteration_stats: Optional[IterationStats],
+               engine_idx: int = 0):
         """Log to prometheus."""
         if scheduler_stats is not None:
-            self.gauge_scheduler_running.set(scheduler_stats.num_running_reqs)
-            self.gauge_scheduler_waiting.set(scheduler_stats.num_waiting_reqs)
+            self.gauge_scheduler_running[engine_idx].set(
+                scheduler_stats.num_running_reqs)
+            self.gauge_scheduler_waiting[engine_idx].set(
+                scheduler_stats.num_waiting_reqs)
 
-            self.gauge_gpu_cache_usage.set(scheduler_stats.kv_cache_usage)
-            self.gauge_kv_cache_usage.set(scheduler_stats.kv_cache_usage)
+            self.gauge_gpu_cache_usage[engine_idx].set(
+                scheduler_stats.kv_cache_usage)
+            self.gauge_kv_cache_usage[engine_idx].set(
+                scheduler_stats.kv_cache_usage)
 
-            self.counter_gpu_prefix_cache_queries.inc(
+            self.counter_gpu_prefix_cache_queries[engine_idx].inc(
                 scheduler_stats.prefix_cache_stats.queries)
-            self.counter_gpu_prefix_cache_hits.inc(
+            self.counter_gpu_prefix_cache_hits[engine_idx].inc(
                 scheduler_stats.prefix_cache_stats.hits)
 
-            self.counter_prefix_cache_queries.inc(
+            self.counter_prefix_cache_queries[engine_idx].inc(
                 scheduler_stats.prefix_cache_stats.queries)
-            self.counter_prefix_cache_hits.inc(
+            self.counter_prefix_cache_hits[engine_idx].inc(
                 scheduler_stats.prefix_cache_stats.hits)
 
             if scheduler_stats.spec_decoding_stats is not None:
@@ -447,42 +519,45 @@ class PrometheusStatLogger(StatLoggerBase):
         if iteration_stats is None:
             return
 
-        self.counter_num_preempted_reqs.inc(iteration_stats.num_preempted_reqs)
-        self.counter_prompt_tokens.inc(iteration_stats.num_prompt_tokens)
-        self.counter_generation_tokens.inc(
+        self.counter_num_preempted_reqs[engine_idx].inc(
+            iteration_stats.num_preempted_reqs)
+        self.counter_prompt_tokens[engine_idx].inc(
+            iteration_stats.num_prompt_tokens)
+        self.counter_generation_tokens[engine_idx].inc(
             iteration_stats.num_generation_tokens)
-        self.histogram_iteration_tokens.observe(
+        self.histogram_iteration_tokens[engine_idx].observe(
             iteration_stats.num_prompt_tokens + \
             iteration_stats.num_generation_tokens)
 
         for max_gen_tokens in iteration_stats.max_num_generation_tokens_iter:
-            self.histogram_max_num_generation_tokens_request.observe(
-                max_gen_tokens)
+            self.histogram_max_num_generation_tokens_request[
+                engine_idx].observe(max_gen_tokens)
         for n_param in iteration_stats.n_params_iter:
-            self.histogram_n_request.observe(n_param)
+            self.histogram_n_request[engine_idx].observe(n_param)
         for ttft in iteration_stats.time_to_first_tokens_iter:
-            self.histogram_time_to_first_token.observe(ttft)
+            self.histogram_time_to_first_token[engine_idx].observe(ttft)
         for tpot in iteration_stats.time_per_output_tokens_iter:
-            self.histogram_time_per_output_token.observe(tpot)
+            self.histogram_time_per_output_token[engine_idx].observe(tpot)
 
         for finished_request in iteration_stats.finished_requests:
-            self.counter_request_success[finished_request.finish_reason].inc()
-            self.histogram_e2e_time_request.observe(
+            self.counter_request_success[
+                finished_request.finish_reason][engine_idx].inc()
+            self.histogram_e2e_time_request[engine_idx].observe(
                 finished_request.e2e_latency)
-            self.histogram_queue_time_request.observe(
+            self.histogram_queue_time_request[engine_idx].observe(
                 finished_request.queued_time)
-            self.histogram_prefill_time_request.observe(
+            self.histogram_prefill_time_request[engine_idx].observe(
                 finished_request.prefill_time)
-            self.histogram_inference_time_request.observe(
+            self.histogram_inference_time_request[engine_idx].observe(
                 finished_request.inference_time)
-            self.histogram_decode_time_request.observe(
+            self.histogram_decode_time_request[engine_idx].observe(
                 finished_request.decode_time)
-            self.histogram_num_prompt_tokens_request.observe(
+            self.histogram_num_prompt_tokens_request[engine_idx].observe(
                 finished_request.num_prompt_tokens)
-            self.histogram_num_generation_tokens_request.observe(
+            self.histogram_num_generation_tokens_request[engine_idx].observe(
                 finished_request.num_generation_tokens)
             if finished_request.max_tokens_param:
-                self.histogram_max_tokens_request.observe(
+                self.histogram_max_tokens_request[engine_idx].observe(
                     finished_request.max_tokens_param)
 
         if self.gauge_lora_info is not None:
@@ -502,6 +577,18 @@ class PrometheusStatLogger(StatLoggerBase):
         self.log_metrics_info("cache_config", self.vllm_config.cache_config)
 
 
+PromMetric = Union[
+    prometheus_client.Gauge,
+    prometheus_client.Counter,
+    prometheus_client.Histogram,
+]
+
+
+def make_per_engine(metric: PromMetric, engine_idxs: list[int],
+                    model_name: str) -> dict[int, PromMetric]:
+    return {idx: metric.labels(model_name, str(idx)) for idx in engine_idxs}
+
+
 def build_buckets(mantissa_lst: list[int], max_value: int) -> list[int]:
     """
     Builds a list of buckets with increasing powers of 10 multiplied by
@@ -529,29 +616,79 @@ def build_1_2_5_buckets(max_value: int) -> list[int]:
     return build_buckets([1, 2, 5], max_value)
 
 
-def setup_default_loggers(
-    vllm_config: VllmConfig,
-    log_stats: bool,
-    engine_num: int,
-    custom_stat_loggers: Optional[list[StatLoggerFactory]] = None,
-) -> list[list[StatLoggerBase]]:
-    """Setup logging and prometheus metrics."""
-    if not log_stats:
-        return []
-
-    factories: list[StatLoggerFactory]
-    if custom_stat_loggers is not None:
-        factories = custom_stat_loggers
-    else:
-        factories = [PrometheusStatLogger]
-        if logger.isEnabledFor(logging.INFO):
-            factories.append(LoggingStatLogger)
-
-    stat_loggers: list[list[StatLoggerBase]] = []
-    for i in range(engine_num):
-        per_engine_stat_loggers: list[StatLoggerBase] = []
-        for logger_factory in factories:
-            per_engine_stat_loggers.append(logger_factory(vllm_config, i))
-        stat_loggers.append(per_engine_stat_loggers)
-
-    return stat_loggers
+class StatLoggerManager:
+    """
+    StatLoggerManager:
+        Logging happens at the level of the EngineCore (per scheduler).
+         * DP: >1 EngineCore per AsyncLLM - loggers for each EngineCore.
+         * With Local Logger, just make N copies for N EngineCores.
+         * With Prometheus, we need a single logger with N "labels"
+
+        This class abstracts away this implementation detail from
+        the AsyncLLM, allowing the AsyncLLM to just call .record()
+        and .log() to a simple interface.
+    """
+
+    def __init__(
+        self,
+        vllm_config: VllmConfig,
+        engine_idxs: Optional[list[int]] = None,
+        custom_stat_loggers: Optional[list[StatLoggerFactory]] = None,
+    ):
+        self.engine_idxs = engine_idxs if engine_idxs else [0]
+
+        factories: list[StatLoggerFactory]
+        if custom_stat_loggers is not None:
+            factories = custom_stat_loggers
+        else:
+            factories = []
+            if logger.isEnabledFor(logging.INFO):
+                factories.append(LoggingStatLogger)
+
+        # engine_idx: StatLogger
+        self.per_engine_logger_dict: dict[int, list[StatLoggerBase]] = {}
+        prometheus_factory = PrometheusStatLogger
+        for engine_idx in self.engine_idxs:
+            loggers: list[StatLoggerBase] = []
+            for logger_factory in factories:
+                # If we get a custom prometheus logger, use that
+                # instead. This is typically used for the ray case.
+                if (isinstance(logger_factory, type)
+                        and issubclass(logger_factory, PrometheusStatLogger)):
+                    prometheus_factory = logger_factory
+                    continue
+                loggers.append(logger_factory(vllm_config,
+                                              engine_idx))  # type: ignore
+            self.per_engine_logger_dict[engine_idx] = loggers
+
+        # For Prometheus, need to share the metrics between EngineCores.
+        # Each EngineCore's metrics are expressed as a unique label.
+        self.prometheus_logger = prometheus_factory(vllm_config, engine_idxs)
+
+    def record(
+        self,
+        scheduler_stats: Optional[SchedulerStats],
+        iteration_stats: Optional[IterationStats],
+        engine_idx: Optional[int] = None,
+    ):
+        if engine_idx is None:
+            engine_idx = 0
+
+        per_engine_loggers = self.per_engine_logger_dict[engine_idx]
+        for logger in per_engine_loggers:
+            logger.record(scheduler_stats, iteration_stats, engine_idx)
+
+        self.prometheus_logger.record(scheduler_stats, iteration_stats,
+                                      engine_idx)
+
+    def log(self):
+        for per_engine_loggers in self.per_engine_logger_dict.values():
+            for logger in per_engine_loggers:
+                logger.log()
+
+    def log_engine_initialized(self):
+        self.prometheus_logger.log_engine_initialized()
+
+        for per_engine_loggers in self.per_engine_logger_dict.values():
+            for logger in per_engine_loggers:
+                logger.log_engine_initialized()

vllm/v1/metrics/ray_wrappers.py

@@ -3,7 +3,6 @@
 import time
 from typing import Optional, Union
 
-from vllm.config import VllmConfig
 from vllm.v1.metrics.loggers import PrometheusStatLogger
 from vllm.v1.spec_decode.metrics import SpecDecodingProm
 
@@ -128,9 +127,6 @@ class RayPrometheusStatLogger(PrometheusStatLogger):
     _histogram_cls = RayHistogramWrapper
     _spec_decoding_cls = RaySpecDecodingProm
 
-    def __init__(self, vllm_config: VllmConfig, engine_index: int = 0):
-        super().__init__(vllm_config, engine_index)
-
     @staticmethod
     def _unregister_vllm_metrics():
         # No-op on purpose