mirror of
https://git.datalinker.icu/vllm-project/vllm.git
synced 2025-12-10 00:06:06 +08:00
463 lines
17 KiB
Python
463 lines
17 KiB
Python
import asyncio
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import time
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from functools import partial
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from typing import Any, Dict, Iterable, List, Optional, Set, Tuple, Type, Union
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from vllm.config import ModelConfig
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from vllm.engine.arg_utils import AsyncEngineArgs
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from vllm.engine.llm_engine import LLMEngine
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from vllm.engine.ray_utils import initialize_cluster, ray
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from vllm.logger import init_logger
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from vllm.outputs import RequestOutput
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from vllm.sampling_params import SamplingParams
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logger = init_logger(__name__)
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class AsyncEngineDeadError(RuntimeError):
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pass
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def _raise_exception_on_finish(task: asyncio.Task,
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request_tracker: "RequestTracker") -> None:
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msg = ("Task finished unexpectedly. This should never happen! "
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"Please open an issue on Github.")
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try:
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try:
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task.result()
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except asyncio.CancelledError:
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return
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except Exception as exc:
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raise AsyncEngineDeadError(
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msg + " See stack trace above for the actual cause.") from exc
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raise AsyncEngineDeadError(msg)
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except Exception as exc:
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request_tracker.propagate_exception(exc)
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raise exc
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class AsyncStream:
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"""A stream of RequestOutputs for a request that can be
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iterated over asynchronously."""
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def __init__(self, request_id: str) -> None:
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self.request_id = request_id
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self._queue = asyncio.Queue()
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self._finished = False
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def put(self, item: RequestOutput) -> None:
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if self._finished:
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return
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self._queue.put_nowait(item)
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def finish(self) -> None:
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self._queue.put_nowait(StopIteration)
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self._finished = True
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@property
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def finished(self) -> bool:
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return self._finished
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def __aiter__(self):
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return self
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async def __anext__(self) -> RequestOutput:
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result = await self._queue.get()
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if result is StopIteration:
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raise StopAsyncIteration
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elif isinstance(result, Exception):
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raise result
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return result
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class RequestTracker:
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"""Synchronous abstraction for tracking requests."""
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def __init__(self) -> None:
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self._request_streams: Dict[str, AsyncStream] = {}
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self._finished_requests: asyncio.Queue[str] = asyncio.Queue()
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self._new_requests: asyncio.Queue[Tuple[AsyncStream,
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dict]] = asyncio.Queue()
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def __contains__(self, item):
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return item in self._request_streams
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def propagate_exception(self, exc: Exception) -> None:
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"""Propagate an exception to all request streams."""
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for stream in self._request_streams.values():
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stream.put(exc)
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def process_request_output(self,
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request_output: RequestOutput,
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*,
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verbose: bool = False) -> None:
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"""Process a request output from the engine."""
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request_id = request_output.request_id
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self._request_streams[request_id].put(request_output)
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if request_output.finished:
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if verbose:
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logger.info(f"Finished request {request_id}.")
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self.abort_request(request_id)
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def add_request(self, request_id: str,
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**engine_add_request_kwargs) -> AsyncStream:
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"""Add a request to be sent to the engine on the next background
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loop iteration."""
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if request_id in self._request_streams:
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raise KeyError(f"Request {request_id} already exists.")
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stream = AsyncStream(request_id)
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self._new_requests.put_nowait((stream, {
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"request_id": request_id,
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**engine_add_request_kwargs
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}))
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return stream
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def abort_request(self, request_id: str, *, verbose: bool = False) -> None:
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"""Abort a request during next background loop iteration."""
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if verbose:
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logger.info(f"Aborted request {request_id}.")
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self._finished_requests.put_nowait(request_id)
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if request_id not in self._request_streams or self._request_streams[
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request_id].finished:
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# The request has already finished or been aborted.
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return
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self._request_streams[request_id].finish()
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def get_new_and_finished_requests(self) -> Tuple[List[dict], Set[str]]:
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"""Get the new requests and finished requests to be
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sent to the engine."""
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new_requests: List[dict] = []
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finished_requests: Set[str] = set()
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while not self._finished_requests.empty():
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request_id = self._finished_requests.get_nowait()
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finished_requests.add(request_id)
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self._request_streams.pop(request_id, None)
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while not self._new_requests.empty():
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stream, new_request = self._new_requests.get_nowait()
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if stream.request_id in finished_requests:
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# The request has already been aborted.
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stream.finish()
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continue
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self._request_streams[stream.request_id] = stream
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new_requests.append(new_request)
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return new_requests, finished_requests
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class _AsyncLLMEngine(LLMEngine):
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"""Extension of LLMEngine to add async methods."""
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async def step_async(self) -> List[RequestOutput]:
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"""Performs one decoding iteration and returns newly generated results.
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The workers are ran asynchronously if possible.
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This function performs one decoding iteration of the engine. It first
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schedules the sequences to be executed in the next iteration and the
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token blocks to be swapped in/out/copy. Then, it executes the model
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and updates the scheduler with the model outputs. Finally, it decodes
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the sequences and returns the newly generated results.
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"""
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(seq_group_metadata_list, scheduler_outputs,
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early_return) = self._schedule()
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if early_return is not None:
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return early_return
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# Execute the model.
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output = await self._run_workers_async(
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"execute_model",
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seq_group_metadata_list=seq_group_metadata_list,
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blocks_to_swap_in=scheduler_outputs.blocks_to_swap_in,
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blocks_to_swap_out=scheduler_outputs.blocks_to_swap_out,
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blocks_to_copy=scheduler_outputs.blocks_to_copy,
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)
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return self._process_model_outputs(output, scheduler_outputs)
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async def _run_workers_async(
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self,
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method: str,
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*args,
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get_all_outputs: bool = False,
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**kwargs,
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) -> Any:
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"""Runs the given method on all workers."""
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all_outputs = []
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for worker in self.workers:
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if self.parallel_config.worker_use_ray:
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executor = partial(worker.execute_method.remote, method)
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else:
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executor = getattr(worker, method)
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output = executor(*args, **kwargs)
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all_outputs.append(output)
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if self.parallel_config.worker_use_ray:
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all_outputs = await asyncio.gather(*all_outputs)
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if get_all_outputs:
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return all_outputs
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# Make sure all workers have the same results.
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output = all_outputs[0]
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for other_output in all_outputs[1:]:
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assert output == other_output
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return output
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class AsyncLLMEngine:
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"""An asynchronous wrapper for LLMEngine.
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This class is used to wrap the LLMEngine class to make it asynchronous. It
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uses asyncio to create a background loop that keeps processing incoming
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requests. The LLMEngine is kicked by the generate method when there
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are requests in the waiting queue. The generate method yields the outputs
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from the LLMEngine to the caller.
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NOTE: For the comprehensive list of arguments, see `LLMEngine`.
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Args:
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worker_use_ray: Whether to use Ray for model workers. Required for
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distributed execution. Should be the same as
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`parallel_config.worker_use_ray`.
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engine_use_ray: Whether to make LLMEngine a Ray actor. If so, the
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async frontend will be executed in a separate process as the
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model workers.
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log_requests: Whether to log the requests.
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start_engine_loop: If True, the background task to run the engine
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will be automatically started in the generate call.
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*args, *kwargs: Arguments for LLMEngine.
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"""
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_engine_class: Type[_AsyncLLMEngine] = _AsyncLLMEngine
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def __init__(self,
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worker_use_ray: bool,
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engine_use_ray: bool,
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*args,
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log_requests: bool = True,
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max_log_len: Optional[int] = None,
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start_engine_loop: bool = True,
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**kwargs) -> None:
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self.worker_use_ray = worker_use_ray
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self.engine_use_ray = engine_use_ray
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self.log_requests = log_requests
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self.max_log_len = max_log_len
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self.engine = self._init_engine(*args, **kwargs)
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self.request_tracker: RequestTracker = RequestTracker()
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self.background_loop = None
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self.start_engine_loop = start_engine_loop
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@property
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def is_running(self) -> bool:
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return (self.background_loop is not None
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and not self.background_loop.done())
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def start_background_loop(self) -> None:
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"""Start the background loop."""
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if self.is_running:
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raise RuntimeError("Background loop is already running.")
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self.background_loop = asyncio.get_event_loop().create_task(
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self.run_engine_loop())
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self.background_loop.add_done_callback(
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partial(_raise_exception_on_finish,
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request_tracker=self.request_tracker))
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def _init_engine(self, *args,
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**kwargs) -> Union[_AsyncLLMEngine, "ray.ObjectRef"]:
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if not self.engine_use_ray:
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engine_class = self._engine_class
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elif self.worker_use_ray:
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engine_class = ray.remote(num_cpus=0)(self._engine_class).remote
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else:
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engine_class = ray.remote(num_gpus=1)(self._engine_class).remote
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return engine_class(*args, **kwargs)
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async def engine_step(self):
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"""Kick the engine to process the waiting requests."""
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new_requests, finished_requests = (
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self.request_tracker.get_new_and_finished_requests())
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for new_request in new_requests:
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# Add the request into the vLLM engine's waiting queue.
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# TODO: Maybe add add_request_batch to reduce Ray overhead
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if self.engine_use_ray:
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await self.engine.add_request.remote(**new_request)
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else:
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self.engine.add_request(**new_request)
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if finished_requests:
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await self._engine_abort(finished_requests)
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if self.engine_use_ray:
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request_outputs = await self.engine.step.remote()
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else:
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request_outputs = await self.engine.step_async()
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# Put the outputs into the corresponding streams.
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for request_output in request_outputs:
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self.request_tracker.process_request_output(
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request_output, verbose=self.log_requests)
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async def _engine_abort(self, request_ids: Iterable[str]):
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if self.engine_use_ray:
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await self.engine.abort_request.remote(request_ids)
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else:
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self.engine.abort_request(request_ids)
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async def run_engine_loop(self):
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while True:
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await self.engine_step()
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await asyncio.sleep(0)
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async def add_request(
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self,
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request_id: str,
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prompt: Optional[str],
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sampling_params: SamplingParams,
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prompt_token_ids: Optional[List[int]] = None,
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arrival_time: Optional[float] = None,
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) -> AsyncStream:
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if self.log_requests:
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shortened_prompt = prompt
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shortened_token_ids = prompt_token_ids
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if self.max_log_len is not None:
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if shortened_prompt is not None:
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shortened_prompt = shortened_prompt[:self.max_log_len]
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if shortened_token_ids is not None:
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shortened_token_ids = shortened_token_ids[:self.
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max_log_len]
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logger.info(f"Received request {request_id}: "
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f"prompt: {shortened_prompt!r}, "
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f"sampling params: {sampling_params}, "
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f"prompt token ids: {shortened_token_ids}.")
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if not self.is_running:
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if self.start_engine_loop:
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self.start_background_loop()
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else:
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raise AsyncEngineDeadError(
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"Background loop is not running. If it was running, "
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"inspect the output to find the stacktrace of the "
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"error that caused the background loop to stop "
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"(AsyncEngineDeadError).")
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stream = self.request_tracker.add_request(
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request_id,
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prompt=prompt,
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sampling_params=sampling_params,
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prompt_token_ids=prompt_token_ids,
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arrival_time=arrival_time)
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return stream
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async def generate(
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self,
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prompt: Optional[str],
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sampling_params: SamplingParams,
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request_id: str,
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prompt_token_ids: Optional[List[int]] = None) -> RequestOutput:
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"""Generate outputs for a request.
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Generate outputs for a request. This method is a coroutine. It adds the
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request into the waiting queue of the LLMEngine and streams the outputs
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from the LLMEngine to the caller.
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Args:
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prompt: The prompt string. Can be None if prompt_token_ids is
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provided.
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sampling_params: The sampling parameters of the request.
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request_id: The unique id of the request.
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prompt_token_ids: The token IDs of the prompt. If None, we
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use the tokenizer to convert the prompts to token IDs.
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Yields:
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The output `RequestOutput` objects from the LLMEngine for the
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request.
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"""
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# Preprocess the request.
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arrival_time = time.time()
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try:
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stream = await self.add_request(request_id,
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prompt,
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sampling_params,
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prompt_token_ids=prompt_token_ids,
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arrival_time=arrival_time)
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async for request_output in stream:
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yield request_output
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except (Exception, asyncio.CancelledError) as e:
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# If there is an exception or coroutine is cancelled, abort the
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# request.
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self._abort(request_id)
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raise e
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async def abort(self, request_id: str) -> None:
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"""Abort a request.
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Abort a submitted request. If the request is finished or not found,
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this method will be a no-op.
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Args:
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request_id: The unique id of the request.
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"""
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if not self.is_running:
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raise AsyncEngineDeadError(
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"Background loop is not running. If it was running, "
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"inspect the output to find the stacktrace of the "
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"error that caused the background loop to stop "
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"(AsyncEngineDeadError).")
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return self._abort(request_id)
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def _abort(self, request_id: str) -> None:
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"""Abort a request.
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Abort a submitted request. If the request is finished or not found,
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this method will be a no-op.
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Args:
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request_id: The unique id of the request.
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"""
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self.request_tracker.abort_request(request_id,
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verbose=self.log_requests)
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async def get_model_config(self) -> ModelConfig:
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"""Get the model configuration of the vLLM engine."""
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if self.engine_use_ray:
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return await self.engine.get_model_config.remote()
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else:
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return self.engine.get_model_config()
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@classmethod
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def from_engine_args(cls,
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engine_args: AsyncEngineArgs,
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start_engine_loop: bool = True) -> "AsyncLLMEngine":
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"""Creates an async LLM engine from the engine arguments."""
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# Create the engine configs.
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engine_configs = engine_args.create_engine_configs()
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parallel_config = engine_configs[2]
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# Initialize the cluster.
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distributed_init_method, placement_group = initialize_cluster(
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parallel_config, engine_args.engine_use_ray)
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# Create the async LLM engine.
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engine = cls(engine_args.worker_use_ray,
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engine_args.engine_use_ray,
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*engine_configs,
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distributed_init_method,
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placement_group,
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log_requests=not engine_args.disable_log_requests,
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log_stats=not engine_args.disable_log_stats,
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max_log_len=engine_args.max_log_len,
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start_engine_loop=start_engine_loop)
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return engine
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