Files
AstrAI/astrai/inference/core/scheduler.py
T
ViperEkura 5c180cfa90 fix : handle zero-token batch generation
- return empty results without running inference for non-positive limits
- keep scheduler batch outputs aligned with requested max_tokens
- add engine and scheduler regression coverage
2026-08-06 12:31:09 +08:00

330 lines
12 KiB
Python

import logging
import threading
import uuid
from typing import Any, Dict, List, Optional, Tuple
import torch
from astrai.inference.core.cache import PagePool
from astrai.inference.core.executor import Executor
from astrai.inference.core.task import STOP, Task, TaskManager, TaskStatus
from astrai.model.automodel import AutoModel
from astrai.tokenize.tokenizer import AutoTokenizer
logger = logging.getLogger(__name__)
class InferenceScheduler:
"""Continuous batching loop: cleanup -> refill -> prefill -> decode (all groups)."""
def __init__(
self,
model: AutoModel,
tokenizer: AutoTokenizer,
max_batch_size: int = 16,
max_seq_len: Optional[int] = None,
device: Optional[str] = None,
dtype: Optional[torch.dtype] = None,
cache: Optional[PagePool] = None,
):
config = model.config
if max_seq_len is not None:
self.max_seq_len = max_seq_len
elif config.max_position_embeddings is not None:
self.max_seq_len = config.max_position_embeddings
else:
raise ValueError(
"max_seq_len must be provided either as argument "
"or in model config (config.max_position_embeddings)"
)
self.device = device or next(model.parameters()).device
self.dtype = dtype or next(model.parameters()).dtype
head_dim = config.hidden_size // config.num_attention_heads
if cache is not None:
self._cache = cache
else:
self._cache = PagePool(
n_layers=config.num_hidden_layers,
n_kv_heads=config.num_key_value_heads,
head_dim=head_dim,
max_batch_size=max_batch_size,
max_seq_len=self.max_seq_len,
device=self.device,
dtype=self.dtype,
)
self._task_mgr = TaskManager(
tokenizer=tokenizer,
max_batch_size=max_batch_size,
max_seq_len=self.max_seq_len,
)
self._executor = Executor(
model=model,
tokenizer=tokenizer,
kv_cache=self._cache,
device=self.device,
dtype=self.dtype,
)
self._stop_event = threading.Event()
self._loop_thread: Optional[threading.Thread] = None
def add_task(self, prompt: str, **kwargs) -> str:
return self._task_mgr.add_task(prompt, **kwargs)
def remove_task(self, task_id: str):
for task in self._task_mgr.remove_task(task_id):
self._cache.task_free(task.task_id)
def get_stats(self) -> Dict[str, Any]:
return self._task_mgr.get_stats()
def _step(
self, tasks: List[Task], return_logprobs: bool = False
) -> Tuple[List[Task], List[Task]]:
"""Advance every active task by one token (prefill + decode).
Single shared primitive for both the continuous-batching loop and
the synchronous ``run_batch`` path, so the two cannot drift.
Tasks must already be allocated in the KV cache. Tasks without output
are prefilled first and sample their first token from the final prompt
position. Tasks with output extend the cache by one position and decode
from their latest generated token.
Args:
tasks: Active tasks to advance by one token.
return_logprobs: Forwarded to ``execute_decode``; per-token
logprobs are recorded on each task's ``output_logprobs``.
Returns:
``(decoded, aborted)``: tasks that produced a new token (its ID
already appended to ``output_ids``) and tasks that hit the
sequence cap and were marked ``ABORTED``.
"""
cache = self._cache
to_prefill = [t for t in tasks if t.output_tokens == 0 and t.prompt_ids]
prefilled_ids = set()
produced: List[Task] = []
if to_prefill:
for t in to_prefill:
t.input_tokens = len(t.prompt_ids)
groups: Dict[Tuple[int, int], List[Task]] = {}
for t in to_prefill:
start_pos = min(cache.task_cached(t.task_id), len(t.prompt_ids) - 1)
groups.setdefault((len(t.prompt_ids), start_pos), []).append(t)
for (prompt_len, start_pos), group in groups.items():
prefilled, step_out = self._executor.execute_prefill(
group, prompt_len, start_pos, return_logprobs=return_logprobs
)
for t, out in zip(prefilled, step_out):
t.output_ids.append(out[0] if return_logprobs else out)
t.output_tokens += 1
prefilled_ids.add(t.task_id)
produced.append(t)
start_logical_page = start_pos // getattr(cache, "page_size", 64)
for t in group:
cache.task_record_hashes(
t.task_id, t.prompt_ids, start_logical_page
)
decoded: List[Task] = []
aborted: List[Task] = []
for t in tasks:
if t.task_id in prefilled_ids:
continue
if cache.task_extend(t.task_id, t.next_pos):
decoded.append(t)
else:
t.status = TaskStatus.ABORTED
aborted.append(t)
if decoded:
step_out = self._executor.execute_decode(
decoded, return_logprobs=return_logprobs
)
for t, out in zip(decoded, step_out):
t.output_ids.append(out[0] if return_logprobs else out)
t.output_tokens += 1
produced.append(t)
return produced, aborted
def _run_generation_loop(self):
stop_ids = self._task_mgr.tokenizer.stop_ids
cache = self._cache
try:
while not self._stop_event.is_set():
finished = self._task_mgr.remove_finished_tasks(stop_ids)
for task in finished:
if task.status == TaskStatus.FINISHED:
cache.task_record_hashes(
task.task_id,
cache.task_cacheable_ids(
task.task_id, task.prompt_ids, task.output_ids
),
)
cache.task_free(task.task_id)
active = self._task_mgr.get_active_tasks()
available = self._task_mgr.max_batch_size - len(active)
if available > 0:
candidates = self._task_mgr.pull_candidates(available)
failed = []
for task in candidates:
if cache.task_alloc(task.task_id, task.prompt_ids):
self._task_mgr.activate(task)
else:
failed.append(task)
if failed:
self._task_mgr.return_to_waiting(failed)
if not self._task_mgr.has_work():
self._task_mgr.wait_for_tasks(timeout=1.0)
continue
active = self._task_mgr.get_active_tasks()
decoded, aborted = self._step(active)
for t in aborted:
self._task_mgr.invoke_callback(t.task_id, STOP)
for t in decoded:
new_text = t.decode_new_token(self._task_mgr.tokenizer)
if new_text:
self._task_mgr.invoke_callback(t.task_id, new_text)
if t.is_finished(stop_ids):
remaining = t.flush_remaining(self._task_mgr.tokenizer)
if remaining:
self._task_mgr.invoke_callback(t.task_id, remaining)
self._task_mgr.invoke_callback(t.task_id, STOP)
except Exception as e:
self._stop_event.set()
logger.error(f"Scheduler loop crashed: {e}", exc_info=True)
for task in self._task_mgr.get_active_tasks():
self._task_mgr.invoke_callback(task.task_id, STOP)
cache.task_free(task.task_id)
for task in self._task_mgr.get_waiting_tasks():
self._task_mgr.invoke_callback(task.task_id, STOP)
self._task_mgr.clear_queues()
def start(self):
if self._loop_thread is not None and self._loop_thread.is_alive():
return
self._stop_event.clear()
t = threading.Thread(target=self._run_generation_loop, daemon=True)
t.start()
self._loop_thread = t
def stop(self):
self._stop_event.set()
self._task_mgr.wake()
if self._loop_thread is not None:
self._loop_thread.join(timeout=2.0)
self._loop_thread = None
for task in self._task_mgr.get_active_tasks():
self._task_mgr.invoke_callback(task.task_id, STOP)
self._cache.task_free(task.task_id)
for task in self._task_mgr.get_waiting_tasks():
self._task_mgr.invoke_callback(task.task_id, STOP)
self._cache.task_free(task.task_id)
self._task_mgr.clear_queues()
if torch.cuda.is_available():
torch.cuda.empty_cache()
def run_batch(
self,
prompt_ids_list: List[List[int]],
*,
max_tokens: Optional[int] = None,
temperature: float = 1.0,
top_p: float = 1.0,
top_k: int = 50,
frequency_penalty: float = 0.0,
rep_window: int = 64,
return_logprobs: bool = False,
) -> List[List[int]]:
"""Synchronous batch generation without the scheduler thread.
Accepts already-tokenized prompts (no string round-trip) and runs
prefill + decode to completion on the calling thread. Designed for
RL rollout, where logprobs of the behaviour policy must be collected
alongside generated tokens.
Args:
prompt_ids_list: ``B`` prompts, each a list of token IDs.
max_tokens: Maximum tokens to generate per prompt. ``None``
uses ``self.max_seq_len - len(prompt_ids)``.
temperature/top_p/top_k/frequency_penalty/rep_window: Sampling
parameters (uniform across the batch).
return_logprobs: If ``True``, return ``(token_ids, logprobs)``
tuples per prompt (logprobs aligned 1-to-1 with token_ids).
Returns:
``List[List[int]]`` of generated token IDs per prompt, or —
when ``return_logprobs`` is ``True`` —
``List[Tuple[List[int], List[float]]]``.
"""
stop_ids = self._task_mgr.tokenizer.stop_ids
cache = self._cache
seq_cap = self.max_seq_len
tasks: List[Task] = []
for ids in prompt_ids_list:
if len(ids) >= seq_cap:
tasks.append(None)
continue
t_max = max_tokens
if t_max is None:
t_max = seq_cap - len(ids)
else:
t_max = min(t_max, seq_cap - len(ids))
if t_max <= 0:
tasks.append(None)
continue
task = Task(
task_id=f"batch_{uuid.uuid4().hex[:8]}",
prompt_ids=list(ids),
max_tokens=t_max,
temperature=temperature,
top_p=top_p,
top_k=top_k,
frequency_penalty=frequency_penalty,
rep_window=rep_window,
)
if not cache.task_alloc(task.task_id, task.prompt_ids):
tasks.append(None)
continue
task.input_tokens = len(task.prompt_ids)
tasks.append(task)
try:
live = [t for t in tasks if t is not None]
while live:
decoded, _ = self._step(live, return_logprobs=return_logprobs)
live = [t for t in decoded if not t.is_finished(stop_ids)]
finally:
for t in tasks:
if t is not None:
cache.task_free(t.task_id)
results: List[Any] = []
for t in tasks:
if t is None:
results.append(([], []) if return_logprobs else [])
elif return_logprobs:
results.append((list(t.output_ids), list(t.output_logprobs)))
else:
results.append(list(t.output_ids))
return results