- add BatchedStreamCallback sink type: TaskManager resolves a decode step's (task_id, token) events under one lock and delivers each sink a single list instead of one call per token - keep the plain Callable[[str]] callback contract: per-token callbacks still receive one call per event, and invoke_callback/cancel_task wrap single events for batched sinks - collect aborted, text, and finish STOP events in the scheduler decode loop and dispatch once per step instead of once per token - register one _ResultSink per generate call (replacing per-task closures) so GenerateResult takes its lock and wakes waiters once per step, with late-bind replay for tasks that start decoding before add_task returns their id - apply GenerateResult batches under a single condition hold via append_batch; append delegates to it - update engine test fakes to the batched contract and add coverage for event grouping, single-event dispatch, cancel STOP, and late-bind replay Benchmark: NVIDIA L20 (idle), CUDA 12.8, torch 2.11.0+cu128, 1.2B bf16 checkpoint, prompt 512, 256 greedy tokens, CUDA graph on, serving-level decode, 3 trials - batch 32: 7.808 -> 7.506 ms/token (4098 -> 4263 batch tok/s, +4.0%) - batch 1/8: unchanged within noise (3.768 -> 3.797 / 4.699 -> 4.607 ms/token) - full suite: 896 passed
366 lines
12 KiB
Python
366 lines
12 KiB
Python
"""Unified inference engine for continuous batching."""
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import asyncio
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import gc
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import logging
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import threading
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from pathlib import Path
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from typing import Any, AsyncGenerator, Dict, Generator, List, Optional, Tuple, Union
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import torch
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import torch.nn as nn
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from astrai.extension import ATTN_BACKEND, AttentionBackend, get_backend
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from astrai.inference.cache import PagePool
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from astrai.inference.scheduler import InferenceScheduler
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from astrai.inference.task import STOP, BatchedStreamCallback
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from astrai.model import AutoModel
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from astrai.tokenize import AutoTokenizer
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logger = logging.getLogger(__name__)
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class GenerateResult:
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"""Thread-safe token accumulator for streaming and non-streaming modes."""
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def __init__(self, count: int = 1):
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self._cond = threading.Condition()
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self._event = threading.Event()
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self.tokens: List[Tuple[int, str]] = []
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self.results: List[str] = [""] * count
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self._done: List[bool] = [False] * count
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self._completed = 0
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self._total = count
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def append(self, token: str, idx: int = 0):
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self.append_batch([(idx, token)])
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def append_batch(self, items: List[Tuple[int, Any]]) -> None:
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"""Append multiple ``(idx, token)`` events under one lock/notify.
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Batched counterpart to :meth:`append` for per-step delivery: state
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updates for every event happen under a single condition hold and
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waiters are woken once per batch instead of once per token.
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"""
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if not items:
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return
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with self._cond:
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for idx, token in items:
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self.tokens.append((idx, token))
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if token is STOP:
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if not self._done[idx]:
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self._done[idx] = True
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self._completed += 1
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self._cond.notify_all()
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else:
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self.results[idx] += token
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self._event.set()
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def pop_all(self) -> List[Tuple[int, str]]:
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with self._cond:
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out = self.tokens.copy()
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self.tokens.clear()
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self._event.clear()
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return out
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def wait(self, timeout: Optional[float] = None) -> bool:
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return self._event.wait(timeout=timeout)
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def wait_completion(self, timeout: float = 300.0):
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with self._cond:
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if not self._cond.wait_for(
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lambda: self._completed >= self._total, timeout=timeout
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):
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raise TimeoutError(
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f"Generation timeout after {timeout}s "
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f"({self._completed}/{self._total} completed)"
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)
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def get_results(self) -> List[str]:
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with self._cond:
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return self.results.copy()
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class _ResultSink(BatchedStreamCallback):
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"""Batched stream channel from the scheduler into one GenerateResult.
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Registered as the ``stream_callback`` for every task of a single
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``generate`` call, so the scheduler's one dispatch per decode step
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maps to one ``append_batch`` (one lock, one waiter wake). A task can
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start decoding the moment ``add_task`` returns — before the engine
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learns its id — so events for ids not yet bound are buffered and
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replayed on ``bind``.
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"""
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def __init__(self, result: GenerateResult):
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self._result = result
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self._lock = threading.Lock()
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self._index_of: Dict[str, int] = {}
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self._pending: List[Tuple[str, Any]] = []
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def bind(self, task_id: str, idx: int) -> None:
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with self._lock:
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self._index_of[task_id] = idx
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replay = [(idx, token) for tid, token in self._pending if tid == task_id]
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if replay:
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self._pending = [
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(tid, token) for tid, token in self._pending if tid != task_id
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]
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if replay:
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self._result.append_batch(replay)
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def __call__(self, events: List[Tuple[str, Any]]) -> None:
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with self._lock:
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items: List[Tuple[int, Any]] = []
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for tid, token in events:
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idx = self._index_of.get(tid)
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if idx is None:
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self._pending.append((tid, token))
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else:
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items.append((idx, token))
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if items:
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self._result.append_batch(items)
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class InferenceEngine:
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"""Unified inference engine backed by continuous-batching scheduler."""
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def __init__(
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self,
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model: nn.Module,
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tokenizer: AutoTokenizer,
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max_batch_size: int = 1,
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max_seq_len: Optional[int] = None,
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cache: Optional[PagePool] = None,
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enable_cuda_graph: bool = True,
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backend: Optional[Union[str, ATTN_BACKEND, AttentionBackend, type]] = None,
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):
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self.model = model
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self.tokenizer = tokenizer
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self.scheduler = InferenceScheduler(
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model=self.model,
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tokenizer=self.tokenizer,
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max_batch_size=max_batch_size,
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max_seq_len=max_seq_len,
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cache=cache,
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enable_cuda_graph=enable_cuda_graph,
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backend=backend,
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)
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self.scheduler.start()
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def __enter__(self):
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return self
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def __exit__(self, exc_type, exc_val, exc_tb):
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self.shutdown()
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return False
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def generate(
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self,
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prompt: Union[str, List[str]],
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stream: bool = False,
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max_tokens: Optional[int] = None,
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temperature: float = 1.0,
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top_p: float = 1.0,
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top_k: int = 50,
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frequency_penalty: float = 0.0,
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rep_window: int = 64,
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) -> Union[Generator, str, List[str]]:
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is_batch = isinstance(prompt, list)
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prompts = prompt if is_batch else [prompt]
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if max_tokens is not None and max_tokens <= 0:
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if stream:
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return iter(())
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results = [""] * len(prompts)
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return results if is_batch else results[0]
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return self._generate(
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prompts,
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is_batch,
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stream,
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max_tokens,
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temperature,
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top_p,
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top_k,
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frequency_penalty,
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rep_window,
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)
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def generate_async(
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self,
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prompt: str,
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max_tokens: Optional[int] = None,
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temperature: float = 1.0,
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top_p: float = 1.0,
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top_k: int = 50,
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frequency_penalty: float = 0.0,
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rep_window: int = 64,
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) -> AsyncGenerator[str, None]:
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request_backend = get_backend(use_default=False)
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result = GenerateResult()
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sink = _ResultSink(result)
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task_id = self.scheduler.add_task(
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prompt=prompt,
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max_tokens=max_tokens,
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temperature=temperature,
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top_p=top_p,
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top_k=top_k,
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frequency_penalty=frequency_penalty,
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rep_window=rep_window,
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backend=request_backend,
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stream_callback=sink,
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)
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sink.bind(task_id, 0)
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async def _agen():
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finished = False
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try:
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while not finished:
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for _idx, token in result.pop_all():
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if token is STOP:
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finished = True
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break
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yield token
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if not finished:
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await asyncio.to_thread(result.wait, 0.05)
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finally:
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if not finished:
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self.scheduler.cancel_task(task_id)
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return _agen()
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def _generate(
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self,
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prompts: List[str],
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is_batch: bool,
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stream: bool,
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max_tokens: Optional[int],
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temperature: float,
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top_p: float,
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top_k: int,
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frequency_penalty: float,
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rep_window: int,
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) -> Union[Generator, str, List[str]]:
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n = len(prompts)
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request_backend = get_backend(use_default=False)
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result = GenerateResult(count=n)
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sink = _ResultSink(result)
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task_ids = []
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for i, p in enumerate(prompts):
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task_id = self.scheduler.add_task(
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prompt=p,
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max_tokens=max_tokens,
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temperature=temperature,
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top_p=top_p,
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top_k=top_k,
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frequency_penalty=frequency_penalty,
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rep_window=rep_window,
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backend=request_backend,
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stream_callback=sink,
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)
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sink.bind(task_id, i)
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task_ids.append(task_id)
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if not stream:
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try:
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result.wait_completion()
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except TimeoutError:
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for tid in task_ids:
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self.scheduler.cancel_task(tid)
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raise
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res = result.get_results()
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return res if is_batch else res[0]
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remaining = n
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finished = [False] * n
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def gen():
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nonlocal remaining
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try:
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while remaining > 0:
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items = result.pop_all()
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for idx, token in items:
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if token is STOP:
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if not finished[idx]:
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finished[idx] = True
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remaining -= 1
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else:
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yield (idx, token) if is_batch else token
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if remaining > 0:
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result.wait(timeout=0.05)
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finally:
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for idx, task_id in enumerate(task_ids):
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if not finished[idx]:
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self.scheduler.cancel_task(task_id)
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return gen()
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def get_stats(self) -> Dict[str, Any]:
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return self.scheduler.get_stats()
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@property
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def backend_name(self) -> str:
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return self.scheduler.backend_name
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@property
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def cuda_graph_enabled(self) -> bool:
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return self.scheduler.cuda_graph_enabled
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def shutdown(self):
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self.scheduler.stop()
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if torch.cuda.is_available():
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torch.cuda.empty_cache()
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gc.collect()
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def build_engine(
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param_path: Optional[Union[str, Path]] = None,
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*,
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model: Optional[nn.Module] = None,
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tokenizer: Optional[AutoTokenizer] = None,
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device: Optional[str] = "cuda",
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dtype: Optional[torch.dtype] = torch.bfloat16,
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max_batch_size: int = 16,
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max_seq_len: Optional[int] = None,
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**engine_kwargs: Any,
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) -> InferenceEngine:
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"""Composition root for inference assembly.
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Loads model and tokenizer from *param_path*, or accepts preloaded
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objects, places the model, and returns a started InferenceEngine.
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Extra *engine_kwargs* (cache, enable_cuda_graph, backend) pass
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through to InferenceEngine. Placement parts left as None are skipped.
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"""
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if param_path is not None:
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if model is not None or tokenizer is not None:
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raise ValueError("pass either param_path or model+tokenizer, not both")
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path = Path(param_path)
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if not path.exists():
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raise FileNotFoundError(f"Parameter directory not found: {path}")
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tokenizer = AutoTokenizer.from_pretrained(path)
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model = AutoModel.from_pretrained(path)
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elif model is None or tokenizer is None:
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raise ValueError("build_engine requires param_path or both model and tokenizer")
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placement: Dict[str, Any] = {}
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if device is not None:
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placement["device"] = device
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if dtype is not None:
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placement["dtype"] = dtype
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if placement:
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model.to(**placement)
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logger.info(
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f"Model placed on {placement.get('device')} "
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f"with dtype {placement.get('dtype')}"
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)
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return InferenceEngine(
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model=model,
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tokenizer=tokenizer,
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max_batch_size=max_batch_size,
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max_seq_len=max_seq_len,
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**engine_kwargs,
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)
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