unsloth/studio/backend/core/inference/gpu_arbiter.py
Daniel Han 899465ed80 Studio: close arbiter load-registration race and surface native progress + local pipeline folders
Publish native sd.cpp generate progress (_gen) before LoRA resolution so a reload probe reads active during setup, matching the diffusers path.

Register the diffusion/video GPU load under the arbiter lock (acquire_for now takes a register callback) so a competing acquire cannot evict an owner before its load is marked in-flight and let two loaders allocate VRAM at once.

Admit local diffusers pipeline folders (root model_index.json, weights in component subdirs) in the local model scan so they reach task tagging and the On Device picker.
2026-07-13 06:31:00 +00:00

98 lines
3.7 KiB
Python

# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
"""Single-GPU arbiter for Studio's heavy GPU consumers.
The chat backends, diffusion, and video share one GPU. Before taking it each calls
``acquire_for(owner)``, which evicts the current other owner so two large models never sit in VRAM
at once. The arbiter only sequences ownership (freeing is each backend's teardown); eviction runs
under the lock, so a transfer is atomic vs other acquires.
"""
from __future__ import annotations
import threading
from typing import Any, Callable, Optional
from loggers import get_logger
logger = get_logger(__name__)
CHAT = "chat"
DIFFUSION = "diffusion"
VIDEO = "video"
_lock = threading.Lock()
_owner: Optional[str] = None
def _evict_chat() -> None:
import time
from core.inference import get_inference_backend
from routes.inference import get_llama_cpp_backend
llama = get_llama_cpp_backend()
# is_active (process exists), not is_loaded (exists AND healthy): a chat model still starting
# up holds VRAM but isn't healthy, so is_loaded would skip it and let the load race diffusion.
if llama.is_active:
llama.unload_model()
orchestrator = get_inference_backend()
if orchestrator.active_model_name:
orchestrator.unload_model(orchestrator.active_model_name)
# Kill the subprocess too: its base CUDA context holds VRAM diffusion needs.
orchestrator._shutdown_subprocess(timeout = 5.0)
# The driver reclaims the killed VRAM asynchronously; wait for it to settle before diffusion
# allocates, else a warm chat->diffusion handoff can transiently OOM.
llama._wait_for_vram_settle(since_kill = time.monotonic())
def _evict_diffusion() -> None:
# Unload whichever engine the router has active (diffusers or native sd.cpp), so a
# chat acquire frees the right one.
from core.inference.diffusion_engine_router import get_active_diffusion_engine
get_active_diffusion_engine().unload()
def _evict_video() -> None:
from core.inference.video import get_video_backend
get_video_backend().unload()
# Patchable in tests via monkeypatch.setitem. Ownership is exclusive, so acquire_for's
# evict-the-current-owner generalises to any number of registered owners.
_EVICTORS = {CHAT: _evict_chat, DIFFUSION: _evict_diffusion, VIDEO: _evict_video}
def acquire_for(owner: str, register: Optional[Callable[[], Any]] = None) -> Any:
"""Make ``owner`` the sole GPU owner, evicting the other if it holds it.
``register``, if given, runs under the arbiter lock right after ownership transfers,
and its return value is returned. Registering the in-flight load HERE -- not after
``acquire_for`` returns -- closes the window where a competing acquire could evict this
owner before its load is marked in-flight: eviction would then find nothing to cancel
and both loaders would allocate VRAM at once. ``register`` must be quick (it holds the
lock) and must not re-enter the arbiter. If it raises, ownership stays with ``owner`` --
matching the pre-register behaviour where a failed load left the handoff in place.
"""
global _owner
if owner not in _EVICTORS:
raise ValueError(f"unknown GPU owner: {owner!r}")
with _lock:
if _owner is not None and _owner != owner:
logger.info("gpu_arbiter: evicting %s for %s", _owner, owner)
_EVICTORS[_owner]()
_owner = owner
return register() if register is not None else None
def release(owner: str) -> None:
"""Drop ``owner``'s claim (no-op if it isn't the current owner)."""
global _owner
with _lock:
if _owner == owner:
_owner = None
def current_owner() -> Optional[str]:
return _owner