llm_engine.py

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project

import time
from collections.abc import Callable, Mapping
from copy import copy
from typing import Any

import torch.nn as nn
from typing_extensions import TypeVar

import vllm.envs as envs
from vllm.config import ParallelConfig, VllmConfig
from vllm.distributed import stateless_destroy_torch_distributed_process_group
from vllm.distributed.parallel_state import get_dp_group
from vllm.engine.arg_utils import EngineArgs
from vllm.inputs import ProcessorInputs, PromptType
from vllm.logger import init_logger
from vllm.lora.request import LoRARequest
from vllm.multimodal import MULTIMODAL_REGISTRY, MultiModalRegistry
from vllm.outputs import PoolingRequestOutput, RequestOutput
from vllm.plugins.io_processors import get_io_processor
from vllm.pooling_params import PoolingParams
from vllm.renderers import renderer_from_config
from vllm.renderers.inputs.preprocess import extract_prompt_components
from vllm.sampling_params import SamplingParams
from vllm.tasks import SupportedTask
from vllm.tokenizers import TokenizerLike
from vllm.tracing import init_tracer
from vllm.usage.usage_lib import UsageContext
from vllm.v1.engine import EngineCoreRequest
from vllm.v1.engine.core_client import EngineCoreClient
from vllm.v1.engine.input_processor import InputProcessor
from vllm.v1.engine.output_processor import OutputProcessor
from vllm.v1.engine.parallel_sampling import ParentRequest
from vllm.v1.executor import Executor
from vllm.v1.metrics.loggers import StatLoggerFactory, StatLoggerManager
from vllm.v1.metrics.reader import Metric, get_metrics_snapshot
from vllm.v1.metrics.stats import IterationStats
from vllm.v1.utils import record_function_or_nullcontext
from vllm.v1.worker.worker_base import WorkerBase

logger = init_logger(__name__)

_R = TypeVar("_R", default=Any)


class LLMEngine:
    """Legacy LLMEngine for backwards compatibility."""

    def __init__(
        self,
        vllm_config: VllmConfig,
        executor_class: type[Executor],
        log_stats: bool,
        aggregate_engine_logging: bool = False,
        usage_context: UsageContext = UsageContext.ENGINE_CONTEXT,
        stat_loggers: list[StatLoggerFactory] | None = None,
        mm_registry: MultiModalRegistry = MULTIMODAL_REGISTRY,
        use_cached_outputs: bool = False,
        multiprocess_mode: bool = False,
    ) -> None:
        self.vllm_config = vllm_config
        self.model_config = vllm_config.model_config
        self.observability_config = vllm_config.observability_config

        tracing_endpoint = self.observability_config.otlp_traces_endpoint
        if tracing_endpoint is not None:
            init_tracer("vllm.llm_engine", tracing_endpoint)

        self.log_stats = log_stats

        parallel_config = vllm_config.parallel_config
        executor_backend = parallel_config.distributed_executor_backend

        self.external_launcher_dp = (
            parallel_config.data_parallel_size > 1
            and executor_backend == "external_launcher"
        )
        # important: init dp group before init the engine_core
        # In the decoupled engine case this is handled in EngineCoreProc.
        if (
            not multiprocess_mode
            and parallel_config.data_parallel_size > 1
            and not self.external_launcher_dp
        ):
            self.dp_group = parallel_config.stateless_init_dp_group()
        else:
            self.dp_group = None
        self.should_execute_dummy_batch = False

        self.renderer = renderer = renderer_from_config(self.vllm_config)
        self.io_processor = get_io_processor(
            self.vllm_config,
            self.model_config.io_processor_plugin,
        )

        # Convert TokPrompt --> EngineCoreRequest.
        self.input_processor = InputProcessor(self.vllm_config, renderer)

        # Converts EngineCoreOutputs --> RequestOutput.
        self.output_processor = OutputProcessor(
            renderer.tokenizer,
            log_stats=self.log_stats,
            stream_interval=self.vllm_config.scheduler_config.stream_interval,
            tracing_enabled=tracing_endpoint is not None,
        )

        # EngineCore (gets EngineCoreRequests and gives EngineCoreOutputs)
        self.engine_core = EngineCoreClient.make_client(
            multiprocess_mode=multiprocess_mode,
            asyncio_mode=False,
            vllm_config=vllm_config,
            executor_class=executor_class,
            log_stats=self.log_stats,
        )

        self.logger_manager: StatLoggerManager | None = None
        if self.log_stats:
            self.logger_manager = StatLoggerManager(
                vllm_config=vllm_config,
                custom_stat_loggers=stat_loggers,
                enable_default_loggers=log_stats,
                aggregate_engine_logging=aggregate_engine_logging,
            )
            self.logger_manager.log_engine_initialized()

        if not multiprocess_mode:
            # for v0 compatibility
            self.model_executor = self.engine_core.engine_core.model_executor  # type: ignore

        if self.external_launcher_dp:
            # If we use DP in external launcher mode, we reuse the
            # existing DP group used for data communication.
            self.dp_group = get_dp_group().cpu_group

        # Don't keep the dummy data in memory
        self.reset_mm_cache()

    @classmethod
    def from_vllm_config(
        cls,
        vllm_config: VllmConfig,
        usage_context: UsageContext = UsageContext.ENGINE_CONTEXT,
        stat_loggers: list[StatLoggerFactory] | None = None,
        disable_log_stats: bool = False,
    ) -> "LLMEngine":
        return cls(
            vllm_config=vllm_config,
            executor_class=Executor.get_class(vllm_config),
            log_stats=(not disable_log_stats),
            usage_context=usage_context,
            stat_loggers=stat_loggers,
            multiprocess_mode=envs.VLLM_ENABLE_V1_MULTIPROCESSING,
        )

    @classmethod
    def from_engine_args(
        cls,
        engine_args: EngineArgs,
        usage_context: UsageContext = UsageContext.ENGINE_CONTEXT,
        stat_loggers: list[StatLoggerFactory] | None = None,
        enable_multiprocessing: bool = False,
    ) -> "LLMEngine":
        """Creates an LLM engine from the engine arguments."""

        # Create the engine configs.
        vllm_config = engine_args.create_engine_config(usage_context)
        executor_class = Executor.get_class(vllm_config)

        if envs.VLLM_ENABLE_V1_MULTIPROCESSING:
            logger.debug("Enabling multiprocessing for LLMEngine.")
            enable_multiprocessing = True

        # Create the LLMEngine.
        return cls(
            vllm_config=vllm_config,
            executor_class=executor_class,
            log_stats=not engine_args.disable_log_stats,
            usage_context=usage_context,
            stat_loggers=stat_loggers,
            multiprocess_mode=enable_multiprocessing,
        )

    def get_num_unfinished_requests(self) -> int:
        return self.output_processor.get_num_unfinished_requests()

    def has_unfinished_requests(self) -> bool:
        has_unfinished = self.output_processor.has_unfinished_requests()
        if self.dp_group is None:
            return has_unfinished or self.engine_core.dp_engines_running()
        return self.has_unfinished_requests_dp(has_unfinished)

    def has_unfinished_requests_dp(self, has_unfinished: bool) -> bool:
        aggregated_has_unfinished = ParallelConfig.has_unfinished_dp(
            self.dp_group, has_unfinished
        )
        if not has_unfinished and aggregated_has_unfinished:
            self.should_execute_dummy_batch = True
        return aggregated_has_unfinished

    @classmethod
    def validate_outputs(cls, outputs, output_type):
        return outputs

    def get_supported_tasks(self) -> tuple[SupportedTask, ...]:
        if not hasattr(self, "_supported_tasks"):
            # Cache the result
            self._supported_tasks = self.engine_core.get_supported_tasks()

        return self._supported_tasks

    def abort_request(self, request_ids: list[str], internal: bool = False) -> None:
        """Remove request_ids from EngineCore and Detokenizer."""

        request_ids = self.output_processor.abort_requests(request_ids, internal)
        self.engine_core.abort_requests(request_ids)

    def add_request(
        self,
        request_id: str,
        prompt: EngineCoreRequest | PromptType | ProcessorInputs,
        params: SamplingParams | PoolingParams,
        arrival_time: float | None = None,
        lora_request: LoRARequest | None = None,
        tokenization_kwargs: dict[str, Any] | None = None,
        trace_headers: Mapping[str, str] | None = None,
        priority: int = 0,
        prompt_text: str | None = None,
    ) -> str:
        # Validate the request_id type.
        if not isinstance(request_id, str):
            raise TypeError(f"request_id must be a string, got {type(request_id)}")

        # Process raw inputs into the request.
        if isinstance(prompt, EngineCoreRequest):
            request = prompt
            if request_id != request.request_id:
                logger.warning_once(
                    "AsyncLLM.add_request() was passed a request_id parameter that "
                    "does not match the EngineCoreRequest.request_id attribute. The "
                    "latter will be used, and the former will be ignored."
                )
        else:
            request = self.input_processor.process_inputs(
                request_id,
                prompt,
                params,
                arrival_time,
                lora_request,
                tokenization_kwargs,
                trace_headers,
                priority,
                supported_tasks=self.get_supported_tasks(),
            )
            prompt_text, _, _ = extract_prompt_components(self.model_config, prompt)

        self.input_processor.assign_request_id(request)

        req_id = request.request_id

        # Use cloned params that may have been updated in process_inputs()
        params = request.params

        n = params.n if isinstance(params, SamplingParams) else 1

        if n == 1:
            # Make a new RequestState and queue.
            self.output_processor.add_request(request, prompt_text, None, 0)
            # Add the request to EngineCore.
            self.engine_core.add_request(request)
            return req_id

        # Fan out child requests (for n>1).
        parent_req = ParentRequest(request)
        for idx in range(n):
            request_id, child_params = parent_req.get_child_info(idx)
            child_request = request if idx == n - 1 else copy(request)
            child_request.request_id = request_id
            child_request.sampling_params = child_params

            # Make a new RequestState and queue.
            self.output_processor.add_request(
                child_request, prompt_text, parent_req, idx
            )
            # Add the request to EngineCore.
            self.engine_core.add_request(child_request)

        return req_id

    def step(self) -> list[RequestOutput | PoolingRequestOutput]:
        if self.should_execute_dummy_batch:
            self.should_execute_dummy_batch = False
            self.engine_core.execute_dummy_batch()
            return []

        # 1) Get EngineCoreOutput from the EngineCore.
        with record_function_or_nullcontext("llm_engine step: get_output"):
            outputs = self.engine_core.get_output()

        # 2) Process EngineCoreOutputs.
        with record_function_or_nullcontext("llm_engine step: process_outputs"):
            iteration_stats = IterationStats() if self.log_stats else None
            processed_outputs = self.output_processor.process_outputs(
                outputs.outputs,
                engine_core_timestamp=outputs.timestamp,
                iteration_stats=iteration_stats,
            )
            self.output_processor.update_scheduler_stats(outputs.scheduler_stats)

        # 3) Abort any reqs that finished due to stop strings.
        with record_function_or_nullcontext("llm_engine step: abort_requests"):
            self.engine_core.abort_requests(processed_outputs.reqs_to_abort)

        # 4) Record stats
        with record_function_or_nullcontext("llm_engine step: record_stats"):
            if (
                self.logger_manager is not None
                and outputs.scheduler_stats is not None
                and len(outputs.outputs) > 0
            ):
                self.logger_manager.record(
                    scheduler_stats=outputs.scheduler_stats,
                    iteration_stats=iteration_stats,
                    mm_cache_stats=self.renderer.stat_mm_cache(),
                )
                self.do_log_stats_with_interval()

        return processed_outputs.request_outputs

    def start_profile(self, profile_prefix: str | None = None):
        self.engine_core.profile(True, profile_prefix)

    def stop_profile(self):
        self.engine_core.profile(False)

    def reset_mm_cache(self):
        self.renderer.clear_mm_cache()
        self.engine_core.reset_mm_cache()

    def reset_prefix_cache(
        self, reset_running_requests: bool = False, reset_connector: bool = False
    ) -> bool:
        return self.engine_core.reset_prefix_cache(
            reset_running_requests, reset_connector
        )

    def reset_encoder_cache(self) -> None:
        """Reset the encoder cache to invalidate all cached encoder outputs.

        This should be called when model weights are updated to ensure
        stale vision embeddings computed with old weights are not reused.
        """
        self.engine_core.reset_encoder_cache()

    def sleep(self, level: int = 1):
        self.engine_core.sleep(level)

        if self.logger_manager is not None:
            self.logger_manager.record_sleep_state(1, level)

    def wake_up(self, tags: list[str] | None = None):
        self.engine_core.wake_up(tags)

        if self.logger_manager is not None:
            self.logger_manager.record_sleep_state(0, 0)

    def is_sleeping(self) -> bool:
        return self.engine_core.is_sleeping()

    def get_metrics(self) -> list[Metric]:
        assert self.log_stats, "Stat logging disabled"
        return get_metrics_snapshot()

    @property
    def tokenizer(self) -> TokenizerLike | None:
        return self.renderer.tokenizer

    def get_tokenizer(self) -> TokenizerLike:
        return self.renderer.get_tokenizer()

    def do_log_stats(self) -> None:
        """Log stats if logging is enabled."""
        if self.logger_manager:
            self.logger_manager.log()

    def do_log_stats_with_interval(self) -> None:
        """Log stats when the time interval has passed."""
        now = time.time()
        if not hasattr(self, "_last_log_time"):
            self._last_log_time = now
        if now - self._last_log_time >= envs.VLLM_LOG_STATS_INTERVAL:
            self.do_log_stats()
            self._last_log_time = now

    def add_lora(self, lora_request: LoRARequest) -> bool:
        """Load a new LoRA adapter into the engine for future requests."""
        return self.engine_core.add_lora(lora_request)

    def remove_lora(self, lora_id: int) -> bool:
        """Remove an already loaded LoRA adapter."""
        return self.engine_core.remove_lora(lora_id)

    def list_loras(self) -> set[int]:
        """List all registered adapters."""
        return self.engine_core.list_loras()

    def pin_lora(self, lora_id: int) -> bool:
        """Prevent an adapter from being evicted."""
        return self.engine_core.pin_lora(lora_id)

    def collective_rpc(
        self,
        method: str | Callable[[WorkerBase], _R],
        timeout: float | None = None,
        args: tuple = (),
        kwargs: dict[str, Any] | None = None,
    ) -> list[_R]:
        return self.engine_core.collective_rpc(method, timeout, args, kwargs)

    def apply_model(self, func: Callable[[nn.Module], _R]) -> list[_R]:
        return self.collective_rpc("apply_model", args=(func,))

    def __del__(self):
        dp_group = getattr(self, "dp_group", None)
        if dp_group is not None and not self.external_launcher_dp:
            stateless_destroy_torch_distributed_process_group(dp_group)