unsloth/studio/backend/core/inference/llama_cpp.py
2026-03-16 11:43:28 +00:00

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# SPDX-License-Identifier: AGPL-3.0-only
# Copyright 2026-present the Unsloth AI Inc. team. All rights reserved. See /studio/LICENSE.AGPL-3.0
"""
llama-server inference backend for GGUF models.
Manages a llama-server subprocess and proxies chat completions
through its OpenAI-compatible /v1/chat/completions endpoint.
"""
import atexit
import json
import struct
import structlog
from loggers import get_logger
import shutil
import signal
import socket
import subprocess
import threading
import time
from pathlib import Path
from typing import Generator, Optional
import httpx
logger = get_logger(__name__)
class LlamaCppBackend:
"""
Manages a llama-server subprocess for GGUF model inference.
Lifecycle:
1. load_model() — starts llama-server with the GGUF file
2. generate_chat_completion() — proxies to /v1/chat/completions, streams back
3. unload_model() — terminates llama-server subprocess
"""
def __init__(self):
self._process: Optional[subprocess.Popen] = None
self._port: Optional[int] = None
self._model_identifier: Optional[str] = None
self._gguf_path: Optional[str] = None
self._hf_repo: Optional[str] = None
self._hf_variant: Optional[str] = None
self._is_vision: bool = False
self._healthy = False
self._context_length: Optional[int] = None
self._chat_template: Optional[str] = None
self._lock = threading.Lock()
self._stdout_lines: list[str] = []
self._stdout_thread: Optional[threading.Thread] = None
self._cancel_event = threading.Event()
self._kill_orphaned_servers()
atexit.register(self._cleanup)
# ── Properties ────────────────────────────────────────────────
@property
def is_loaded(self) -> bool:
return self._process is not None and self._healthy
@property
def is_active(self) -> bool:
"""True if a llama-server process exists (loading or loaded)."""
return self._process is not None
@property
def base_url(self) -> str:
return f"http://127.0.0.1:{self._port}"
@property
def model_identifier(self) -> Optional[str]:
return self._model_identifier
@property
def is_vision(self) -> bool:
return self._is_vision
@property
def hf_variant(self) -> Optional[str]:
return self._hf_variant
@property
def context_length(self) -> Optional[int]:
return self._context_length
@property
def chat_template(self) -> Optional[str]:
return self._chat_template
# ── Binary discovery ──────────────────────────────────────────
@staticmethod
def _find_llama_server_binary() -> Optional[str]:
"""
Locate the llama-server binary.
Search order:
1. LLAMA_SERVER_PATH environment variable (direct path to binary)
1b. UNSLOTH_LLAMA_CPP_PATH env var (custom llama.cpp install dir)
2. ~/.unsloth/llama.cpp/llama-server (make build, root dir)
3. ~/.unsloth/llama.cpp/build/bin/llama-server (cmake build, Linux)
4. ~/.unsloth/llama.cpp/build/bin/Release/llama-server.exe (cmake build, Windows)
5. ./llama.cpp/llama-server (legacy: make build, root dir)
6. ./llama.cpp/build/bin/llama-server (legacy: cmake in-tree build)
7. llama-server on PATH (system install)
8. ./bin/llama-server (legacy: extracted binary)
"""
import os
import sys
binary_name = "llama-server.exe" if sys.platform == "win32" else "llama-server"
# 1. Env var — direct path to binary
env_path = os.environ.get("LLAMA_SERVER_PATH")
if env_path and Path(env_path).is_file():
return env_path
# 1b. UNSLOTH_LLAMA_CPP_PATH — custom llama.cpp install directory
custom_llama_cpp = os.environ.get("UNSLOTH_LLAMA_CPP_PATH")
if custom_llama_cpp:
custom_dir = Path(custom_llama_cpp)
# Root dir (make builds)
root_bin = custom_dir / binary_name
if root_bin.is_file():
return str(root_bin)
# build/bin/ (cmake builds on Linux)
cmake_bin = custom_dir / "build" / "bin" / binary_name
if cmake_bin.is_file():
return str(cmake_bin)
# build/bin/Release/ (cmake builds on Windows)
if sys.platform == "win32":
win_bin = custom_dir / "build" / "bin" / "Release" / binary_name
if win_bin.is_file():
return str(win_bin)
# 24. ~/.unsloth/llama.cpp (primary — setup.sh / setup.ps1 build here)
unsloth_home = Path.home() / ".unsloth" / "llama.cpp"
# Root dir (make builds copy binaries here)
home_root = unsloth_home / binary_name
if home_root.is_file():
return str(home_root)
# build/bin/ (cmake builds on Linux)
home_linux = unsloth_home / "build" / "bin" / binary_name
if home_linux.is_file():
return str(home_linux)
# 3. Windows MSVC build has Release subdir
if sys.platform == "win32":
home_win = unsloth_home / "build" / "bin" / "Release" / binary_name
if home_win.is_file():
return str(home_win)
# 56. Legacy: in-tree build (older setup.sh / setup.ps1 versions)
project_root = Path(__file__).resolve().parents[4]
# Root dir (make builds)
root_path = project_root / "llama.cpp" / binary_name
if root_path.is_file():
return str(root_path)
# build/bin/ (cmake builds)
build_path = project_root / "llama.cpp" / "build" / "bin" / binary_name
if build_path.is_file():
return str(build_path)
if sys.platform == "win32":
win_path = (
project_root / "llama.cpp" / "build" / "bin" / "Release" / binary_name
)
if win_path.is_file():
return str(win_path)
# 7. System PATH
system_path = shutil.which("llama-server")
if system_path:
return system_path
# 8. Legacy: extracted to bin/
bin_path = project_root / "bin" / binary_name
if bin_path.is_file():
return str(bin_path)
return None
# ── GPU allocation ────────────────────────────────────────────
@staticmethod
def _get_gguf_size_bytes(model_path: str) -> int:
"""Get total GGUF size in bytes, including split shards."""
import re
main = Path(model_path)
total = main.stat().st_size
# Check for split shards (e.g., model-00001-of-00003.gguf)
shard_pat = re.compile(r"^(.*)-(\d{5})-of-(\d{5})\.gguf$")
m = shard_pat.match(main.name)
if m:
prefix, _, num_total = m.group(1), m.group(2), m.group(3)
sibling_pat = re.compile(
r"^"
+ re.escape(prefix)
+ r"-\d{5}-of-"
+ re.escape(num_total)
+ r"\.gguf$"
)
for sibling in main.parent.iterdir():
if sibling != main and sibling_pat.match(sibling.name):
total += sibling.stat().st_size
return total
@staticmethod
def _get_gpu_free_memory() -> list[tuple[int, int]]:
"""Query free memory per GPU via nvidia-smi.
Returns list of (gpu_index, free_mib) sorted by index.
Respects CUDA_VISIBLE_DEVICES if set.
Returns empty list if nvidia-smi is not available.
"""
import os
try:
result = subprocess.run(
[
"nvidia-smi",
"--query-gpu=index,memory.free",
"--format=csv,noheader,nounits",
],
capture_output = True,
text = True,
timeout = 10,
)
if result.returncode != 0:
return []
# Parse which GPUs are allowed by existing CUDA_VISIBLE_DEVICES
allowed = None
cvd = os.environ.get("CUDA_VISIBLE_DEVICES")
if cvd is not None and cvd.strip():
try:
allowed = set(int(x.strip()) for x in cvd.split(","))
except ValueError:
pass # Non-numeric (e.g., "GPU-uuid"), ignore filter
gpus = []
for line in result.stdout.strip().splitlines():
parts = line.split(",")
if len(parts) == 2:
idx = int(parts[0].strip())
free_mib = int(parts[1].strip())
if allowed is not None and idx not in allowed:
continue
gpus.append((idx, free_mib))
return gpus
except Exception:
return []
@staticmethod
def _select_gpus(
model_size_bytes: int,
gpus: list[tuple[int, int]],
) -> tuple[Optional[list[int]], bool]:
"""Pick GPU(s) for a model based on file size and free memory.
Uses GGUF file size as a rough proxy for VRAM usage (actual usage
is higher due to KV cache and compute buffers, but 70% threshold
accounts for that).
Returns (gpu_indices, use_fit):
- ([1], False) model fits on 1 GPU at 70% of free
- ([1, 2], False) model needs 2 GPUs
- (None, True) model too large, let --fit handle it
"""
if not gpus:
return None, True
model_size_mib = model_size_bytes / (1024 * 1024)
# Sort GPUs by free memory descending
ranked = sorted(gpus, key = lambda g: g[1], reverse = True)
# Try fitting on 1 GPU (70% of free memory threshold)
if ranked[0][1] * 0.70 >= model_size_mib:
return [ranked[0][0]], False
# Try fitting on N GPUs (accumulate free memory from most-free)
cumulative = 0
selected = []
for idx, free_mib in ranked:
selected.append(idx)
cumulative += free_mib * 0.70
if cumulative >= model_size_mib:
return sorted(selected), False
# Model is too large even for all GPUs, let --fit handle it
return None, True
# ── Variant fallback ────────────────────────────────────────────
@staticmethod
def _find_smallest_fitting_variant(
hf_repo: str,
free_bytes: int,
hf_token: Optional[str] = None,
) -> Optional[tuple[str, int]]:
"""Find the smallest GGUF variant (including all shards) that fits.
Groups split shards by variant prefix and sums their sizes.
For example, UD-Q4_K_XL with 9 shards of 50 GB each = 450 GB total.
Returns (first_shard_filename, total_size_bytes) or None if nothing fits.
"""
import re
try:
from huggingface_hub import get_paths_info, list_repo_files
files = list_repo_files(hf_repo, token = hf_token)
gguf_files = [
f for f in files if f.endswith(".gguf") and "mmproj" not in f.lower()
]
if not gguf_files:
return None
# Get sizes for all GGUF files
path_infos = list(get_paths_info(hf_repo, gguf_files, token = hf_token))
size_map = {p.path: (p.size or 0) for p in path_infos}
# Group files by variant: shards share a prefix before -NNNNN-of-NNNNN
shard_pat = re.compile(r"^(.*)-\d{5}-of-\d{5}\.gguf$")
variants: dict[str, list[str]] = {}
for f in gguf_files:
m = shard_pat.match(f)
key = m.group(1) if m else f
variants.setdefault(key, []).append(f)
# Sum shard sizes per variant, track the first shard (for download)
variant_sizes: list[tuple[str, int, list[str]]] = []
for key, shard_files in variants.items():
total = sum(size_map.get(f, 0) for f in shard_files)
first = sorted(shard_files)[0]
variant_sizes.append((first, total, shard_files))
# Sort by total size ascending and pick the smallest that fits
variant_sizes.sort(key = lambda x: x[1])
for first_file, total_size, _ in variant_sizes:
if total_size > 0 and total_size <= free_bytes:
return first_file, total_size
return None
except Exception:
return None
# ── Port allocation ───────────────────────────────────────────
@staticmethod
def _find_free_port() -> int:
"""Find an available TCP port."""
with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as s:
s.bind(("127.0.0.1", 0))
return s.getsockname()[1]
# ── Stdout drain (prevents pipe deadlock on Windows) ─────────
def _drain_stdout(self):
"""
Read lines from the subprocess stdout in a background thread.
This prevents a pipe-buffer deadlock on Windows where the default
pipe buffer is only ~4 KB. Without draining, llama-server blocks
on writes and never becomes healthy.
"""
try:
for line in self._process.stdout:
line = line.rstrip()
if line:
self._stdout_lines.append(line)
logger.info(f"[llama-server] {line}")
except (ValueError, OSError):
# Pipe closed — process is terminating
pass
# GGUF KV type sizes for fast skipping
_GGUF_TYPE_SIZE = {
0: 1,
1: 1,
2: 2,
3: 2,
4: 4,
5: 4,
6: 4,
7: 1,
10: 8,
11: 8,
12: 8,
}
@staticmethod
def _gguf_skip_value(f, vtype: int) -> None:
"""Skip a GGUF KV value without reading it."""
sz = LlamaCppBackend._GGUF_TYPE_SIZE.get(vtype)
if sz is not None:
f.seek(sz, 1)
elif vtype == 8: # STRING
slen = struct.unpack("<Q", f.read(8))[0]
f.seek(slen, 1)
elif vtype == 9: # ARRAY
atype = struct.unpack("<I", f.read(4))[0]
alen = struct.unpack("<Q", f.read(8))[0]
elem_sz = LlamaCppBackend._GGUF_TYPE_SIZE.get(atype)
if elem_sz is not None:
f.seek(elem_sz * alen, 1)
elif atype == 8:
for _ in range(alen):
slen = struct.unpack("<Q", f.read(8))[0]
f.seek(slen, 1)
else:
for _ in range(alen):
LlamaCppBackend._gguf_skip_value(f, atype)
def _read_gguf_metadata(self, gguf_path: str) -> None:
"""Read context_length and chat_template from a GGUF file's KV header.
Parses only the KV pairs we need (~30ms even for multi-GB files).
For split GGUFs, metadata is always in shard 1.
"""
try:
WANTED = {"general.architecture", "tokenizer.chat_template"}
arch = None
ctx_key = None
with open(gguf_path, "rb") as f:
magic = struct.unpack("<I", f.read(4))[0]
if magic != 0x46554747: # b"GGUF" as little-endian u32
return
_version = struct.unpack("<I", f.read(4))[0]
_tensor_count, kv_count = struct.unpack("<QQ", f.read(16))
for _ in range(kv_count):
key_len = struct.unpack("<Q", f.read(8))[0]
key = f.read(key_len).decode("utf-8")
vtype = struct.unpack("<I", f.read(4))[0]
if key in WANTED or (ctx_key and key == ctx_key):
# Read this value
if vtype == 8: # STRING
slen = struct.unpack("<Q", f.read(8))[0]
val_s = f.read(slen).decode("utf-8")
if key == "general.architecture":
arch = val_s
ctx_key = f"{arch}.context_length"
elif key == "tokenizer.chat_template":
self._chat_template = val_s
elif vtype == 4: # UINT32
val_i = struct.unpack("<I", f.read(4))[0]
if ctx_key and key == ctx_key:
self._context_length = val_i
elif vtype == 10: # UINT64
val_i = struct.unpack("<Q", f.read(8))[0]
if ctx_key and key == ctx_key:
self._context_length = val_i
else:
self._gguf_skip_value(f, vtype)
else:
self._gguf_skip_value(f, vtype)
if self._context_length:
logger.info(f"GGUF metadata: context_length={self._context_length}")
if self._chat_template:
logger.info(
f"GGUF metadata: chat_template={len(self._chat_template)} chars"
)
except Exception as e:
logger.warning(f"Failed to read GGUF metadata: {e}")
# ── HF download (no lock held) ───────────────────────────────
def _download_gguf(
self,
*,
hf_repo: str,
hf_variant: Optional[str] = None,
hf_token: Optional[str] = None,
) -> str:
"""Download GGUF file(s) from HuggingFace. Returns local path.
Runs WITHOUT self._lock so that unload_model() can set
_cancel_event at any time. Checks _cancel_event between
each shard download.
"""
try:
from huggingface_hub import hf_hub_download
except ImportError:
raise RuntimeError(
"huggingface_hub is required for HF model loading. "
"Install it with: pip install huggingface_hub"
)
# Determine the filename from the variant
gguf_filename = None
gguf_extra_shards: list[str] = []
if hf_variant:
try:
import re
from huggingface_hub import list_repo_files
files = list_repo_files(hf_repo, token = hf_token)
variant_lower = hf_variant.lower()
boundary = re.compile(
r"(?<![a-zA-Z0-9])" + re.escape(variant_lower) + r"(?![a-zA-Z0-9])"
)
gguf_files = sorted(
f
for f in files
if f.endswith(".gguf") and boundary.search(f.lower())
)
if gguf_files:
gguf_filename = gguf_files[0]
shard_pat = re.compile(r"^(.*)-\d{5}-of-(\d{5})\.gguf$")
m = shard_pat.match(gguf_filename)
if m:
prefix = m.group(1)
total = m.group(2)
sibling_pat = re.compile(
r"^"
+ re.escape(prefix)
+ r"-\d{5}-of-"
+ re.escape(total)
+ r"\.gguf$"
)
gguf_extra_shards = [
f for f in gguf_files[1:] if sibling_pat.match(f)
]
except Exception as e:
logger.warning(f"Could not list repo files: {e}")
if not gguf_filename:
repo_name = hf_repo.split("/")[-1].replace("-GGUF", "")
gguf_filename = f"{repo_name}-{hf_variant}.gguf"
# Check disk space and fall back to a smaller variant if needed
all_gguf_files = [gguf_filename] + gguf_extra_shards
try:
import os
from huggingface_hub import get_paths_info
path_infos = list(get_paths_info(hf_repo, all_gguf_files, token = hf_token))
total_download_bytes = sum((p.size or 0) for p in path_infos)
if total_download_bytes > 0:
cache_dir = os.environ.get(
"HF_HUB_CACHE",
str(Path.home() / ".cache" / "huggingface" / "hub"),
)
Path(cache_dir).mkdir(parents = True, exist_ok = True)
free_bytes = shutil.disk_usage(cache_dir).free
total_gb = total_download_bytes / (1024**3)
free_gb = free_bytes / (1024**3)
logger.info(
f"GGUF download: {total_gb:.1f} GB needed, "
f"{free_gb:.1f} GB free on disk"
)
if total_download_bytes > free_bytes:
smaller = self._find_smallest_fitting_variant(
hf_repo,
free_bytes,
hf_token,
)
if smaller:
fallback_file, fallback_size = smaller
logger.info(
f"Selected variant too large ({total_gb:.1f} GB), "
f"falling back to {fallback_file} ({fallback_size / (1024**3):.1f} GB)"
)
gguf_filename = fallback_file
import re as _re
_shard_pat = _re.compile(r"^(.*)-\d{5}-of-\d{5}\.gguf$")
_m = _shard_pat.match(gguf_filename)
_prefix = _m.group(1) if _m else None
if _prefix:
gguf_extra_shards = sorted(
f
for f in all_gguf_files
if f.startswith(_prefix)
and f != gguf_filename
and "mmproj" not in f.lower()
)
else:
gguf_extra_shards = []
else:
raise RuntimeError(
f"Not enough disk space to download any variant. "
f"Only {free_gb:.1f} GB free in {cache_dir}"
)
except RuntimeError:
raise
except Exception as e:
logger.warning(f"Could not check disk space: {e}")
logger.info(
f"Downloading GGUF: {hf_repo}/{gguf_filename}"
+ (f" (+{len(gguf_extra_shards)} shards)" if gguf_extra_shards else "")
)
try:
if self._cancel_event.is_set():
raise RuntimeError("Cancelled")
local_path = hf_hub_download(
repo_id = hf_repo,
filename = gguf_filename,
token = hf_token,
)
for shard in gguf_extra_shards:
if self._cancel_event.is_set():
raise RuntimeError("Cancelled")
logger.info(f"Downloading GGUF shard: {shard}")
hf_hub_download(
repo_id = hf_repo,
filename = shard,
token = hf_token,
)
except RuntimeError as e:
if "Cancelled" in str(e):
raise
raise RuntimeError(
f"Failed to download GGUF file '{gguf_filename}' from {hf_repo}: {e}"
)
except Exception as e:
raise RuntimeError(
f"Failed to download GGUF file '{gguf_filename}' from {hf_repo}: {e}"
)
logger.info(f"GGUF downloaded to: {local_path}")
return local_path
def _download_mmproj(
self,
*,
hf_repo: str,
hf_token: Optional[str] = None,
) -> Optional[str]:
"""Download the mmproj (vision projection) file from a GGUF repo.
Prefers mmproj-F16.gguf, falls back to any mmproj*.gguf file.
Returns the local path, or None if no mmproj file exists.
"""
try:
from huggingface_hub import hf_hub_download, list_repo_files
files = list_repo_files(hf_repo, token = hf_token)
mmproj_files = sorted(
f for f in files if f.endswith(".gguf") and "mmproj" in f.lower()
)
if not mmproj_files:
return None
# Prefer F16 variant
target = None
for f in mmproj_files:
if "f16" in f.lower():
target = f
break
if target is None:
target = mmproj_files[0]
logger.info(f"Downloading mmproj: {hf_repo}/{target}")
local_path = hf_hub_download(
repo_id = hf_repo,
filename = target,
token = hf_token,
)
return local_path
except Exception as e:
logger.warning(f"Could not download mmproj: {e}")
return None
# ── Lifecycle ─────────────────────────────────────────────────
def load_model(
self,
*,
# Local mode: pass a path to a .gguf file
gguf_path: Optional[str] = None,
# Vision projection (mmproj) for local vision models
mmproj_path: Optional[str] = None,
# HF mode: let llama-server download via -hf "repo:quant"
hf_repo: Optional[str] = None,
hf_variant: Optional[str] = None,
hf_token: Optional[str] = None,
# Common
model_identifier: str,
is_vision: bool = False,
n_ctx: int = 4096,
n_threads: Optional[int] = None,
n_gpu_layers: Optional[int] = None, # Accepted for caller compat, unused
) -> bool:
"""
Start llama-server with a GGUF model.
Two modes:
- Local: ``gguf_path="/path/to/model.gguf"`` → uses ``-m``
- HF: ``hf_repo="unsloth/gemma-3-4b-it-GGUF", hf_variant="Q4_K_M"`` → uses ``-hf``
In HF mode, llama-server handles downloading, caching, and
auto-loading mmproj files for vision models.
Returns True if server started and health check passed.
"""
self._cancel_event.clear()
# ── Phase 1: kill old process (under lock, fast) ──────────
with self._lock:
self._kill_process()
binary = self._find_llama_server_binary()
if not binary:
raise RuntimeError(
"llama-server binary not found. "
"Run setup.sh to build it, install llama.cpp, "
"or set LLAMA_SERVER_PATH environment variable."
)
# ── Phase 2: download (NO lock held, so cancel can proceed) ──
if hf_repo:
model_path = self._download_gguf(
hf_repo = hf_repo,
hf_variant = hf_variant,
hf_token = hf_token,
)
# Auto-download mmproj for vision models
if is_vision and not mmproj_path:
mmproj_path = self._download_mmproj(
hf_repo = hf_repo,
hf_token = hf_token,
)
elif gguf_path:
if not Path(gguf_path).is_file():
raise FileNotFoundError(f"GGUF file not found: {gguf_path}")
model_path = gguf_path
else:
raise ValueError("Either gguf_path or hf_repo must be provided")
# Read GGUF metadata (context_length, chat_template) -- fast, header only
self._read_gguf_metadata(model_path)
# Check cancel after download
if self._cancel_event.is_set():
logger.info("Load cancelled after download phase")
return False
# ── Phase 3: start llama-server (under lock) ──────────────
with self._lock:
# Re-check cancel inside lock
if self._cancel_event.is_set():
logger.info("Load cancelled before server start")
return False
self._port = self._find_free_port()
# Select GPU(s) based on model size and free memory
try:
model_size = self._get_gguf_size_bytes(model_path)
gpus = self._get_gpu_free_memory()
gpu_indices, use_fit = self._select_gpus(model_size, gpus)
logger.info(
f"GGUF size: {model_size / (1024**3):.1f} GB, "
f"GPUs free: {gpus}, selected: {gpu_indices}, fit: {use_fit}"
)
except Exception as e:
logger.warning(f"GPU selection failed ({e}), using --fit on")
gpu_indices, use_fit = None, True
cmd = [
binary,
"-m",
model_path,
"--port",
str(self._port),
"-c",
"0", # 0 = use model's native context size
"--parallel",
"1", # Single-user studio, saves VRAM
"--flash-attn",
"on", # Force flash attention for speed
]
if use_fit:
cmd.extend(["--fit", "on"])
if n_threads is not None:
cmd.extend(["--threads", str(n_threads)])
if mmproj_path:
if not Path(mmproj_path).is_file():
logger.warning(f"mmproj file not found: {mmproj_path}")
else:
cmd.extend(["--mmproj", mmproj_path])
logger.info(f"Using mmproj for vision: {mmproj_path}")
logger.info(f"Starting llama-server: {' '.join(cmd)}")
# Set library paths so llama-server can find its shared libs and CUDA DLLs
import os
import sys
env = os.environ.copy()
binary_dir = str(Path(binary).parent)
if sys.platform == "win32":
# On Windows, CUDA DLLs (cublas64_12.dll, cudart64_12.dll, etc.)
# must be on PATH. Add CUDA_PATH\bin if available.
path_dirs = [binary_dir]
cuda_path = os.environ.get("CUDA_PATH", "")
if cuda_path:
cuda_bin = os.path.join(cuda_path, "bin")
if os.path.isdir(cuda_bin):
path_dirs.append(cuda_bin)
# Some CUDA installs put DLLs in bin\x64
cuda_bin_x64 = os.path.join(cuda_path, "bin", "x64")
if os.path.isdir(cuda_bin_x64):
path_dirs.append(cuda_bin_x64)
existing_path = env.get("PATH", "")
env["PATH"] = ";".join(path_dirs) + ";" + existing_path
else:
# Linux: set LD_LIBRARY_PATH for shared libs next to the binary
existing_ld = env.get("LD_LIBRARY_PATH", "")
env["LD_LIBRARY_PATH"] = (
f"{binary_dir}:{existing_ld}" if existing_ld else binary_dir
)
# Pin to selected GPU(s) via CUDA_VISIBLE_DEVICES
if gpu_indices is not None:
env["CUDA_VISIBLE_DEVICES"] = ",".join(str(i) for i in gpu_indices)
self._stdout_lines = []
self._process = subprocess.Popen(
cmd,
stdout = subprocess.PIPE,
stderr = subprocess.STDOUT,
text = True,
env = env,
)
# Start background thread to drain stdout and prevent pipe deadlock
self._stdout_thread = threading.Thread(
target = self._drain_stdout, daemon = True, name = "llama-stdout"
)
self._stdout_thread.start()
self._gguf_path = gguf_path
self._hf_repo = hf_repo
self._hf_variant = hf_variant
self._is_vision = is_vision
self._model_identifier = model_identifier
# Wait for llama-server to become healthy
if not self._wait_for_health(timeout = 120.0):
self._kill_process()
raise RuntimeError(
"llama-server failed to start. "
"Check that the GGUF file is valid and you have enough memory."
)
self._healthy = True
logger.info(
f"llama-server ready on port {self._port} "
f"for model '{model_identifier}'"
)
return True
def unload_model(self) -> bool:
"""Terminate the llama-server subprocess and cancel any in-flight download."""
self._cancel_event.set()
with self._lock:
self._kill_process()
logger.info(f"Unloaded GGUF model: {self._model_identifier}")
self._model_identifier = None
self._gguf_path = None
self._hf_repo = None
self._hf_variant = None
self._is_vision = False
self._is_audio = False
self._audio_type = None
self._port = None
self._healthy = False
self._context_length = None
self._chat_template = None
# Free audio codec GPU memory
if LlamaCppBackend._codec_mgr is not None:
LlamaCppBackend._codec_mgr.unload()
LlamaCppBackend._codec_mgr = None
import torch
if torch.cuda.is_available():
torch.cuda.empty_cache()
return True
def _kill_process(self):
"""Terminate the subprocess if running."""
if self._process is None:
return
try:
self._process.terminate()
self._process.wait(timeout = 5)
except subprocess.TimeoutExpired:
logger.warning("llama-server did not exit on SIGTERM, sending SIGKILL")
self._process.kill()
self._process.wait(timeout = 5)
except Exception as e:
logger.warning(f"Error killing llama-server process: {e}")
finally:
self._process = None
if self._stdout_thread is not None:
self._stdout_thread.join(timeout = 2)
self._stdout_thread = None
@staticmethod
def _kill_orphaned_servers():
"""Kill orphaned llama-server processes started by studio.
Only kills processes whose binary lives under ~/.unsloth/llama.cpp/
to avoid terminating unrelated llama-server instances on the machine.
"""
import os
import signal
try:
# Use pgrep with full command match to identify studio-managed servers
result = subprocess.run(
["pgrep", "-a", "-f", "llama-server"],
capture_output = True,
text = True,
timeout = 5,
)
if result.returncode != 0:
return
for line in result.stdout.strip().splitlines():
parts = line.strip().split(None, 1)
if len(parts) < 2:
continue
pid = int(parts[0])
cmdline = parts[1]
if pid == os.getpid():
continue
# Only kill if it's a studio-managed server (lives under .unsloth/)
if ".unsloth/" not in cmdline and "unsloth" not in cmdline.lower():
continue
try:
os.kill(pid, signal.SIGKILL)
logger.info(f"Killed orphaned llama-server process (pid={pid})")
except ProcessLookupError:
pass
except PermissionError:
pass
except Exception:
pass
def _cleanup(self):
"""atexit handler to ensure llama-server is terminated."""
self._kill_process()
def _wait_for_health(self, timeout: float = 120.0, interval: float = 0.5) -> bool:
"""
Poll llama-server's /health endpoint until it responds 200.
Also monitors subprocess for early exit/crash.
"""
deadline = time.monotonic() + timeout
url = f"http://127.0.0.1:{self._port}/health"
while time.monotonic() < deadline:
# Check if process crashed
if self._process.poll() is not None:
# Give the drain thread a moment to collect final output
if self._stdout_thread is not None:
self._stdout_thread.join(timeout = 2)
output = "\n".join(self._stdout_lines[-50:])
logger.error(
f"llama-server exited with code {self._process.returncode}. "
f"Output: {output[:2000]}"
)
return False
try:
resp = httpx.get(url, timeout = 2.0)
if resp.status_code == 200:
return True
except (httpx.ConnectError, httpx.TimeoutException):
pass
time.sleep(interval)
logger.error(f"llama-server health check timed out after {timeout}s")
return False
# ── Message building (OpenAI format) ──────────────────────────
@staticmethod
def _build_openai_messages(
messages: list[dict],
image_b64: Optional[str] = None,
) -> list[dict]:
"""
Build OpenAI-format messages, optionally injecting an image_url
content part into the last user message for vision models.
If no image is provided, returns messages as-is.
"""
if not image_b64:
return messages
# Find the last user message and convert to multimodal content parts
result = [msg.copy() for msg in messages]
last_user_idx = None
for i, msg in enumerate(result):
if msg["role"] == "user":
last_user_idx = i
if last_user_idx is not None:
text_content = result[last_user_idx].get("content", "")
result[last_user_idx]["content"] = [
{"type": "text", "text": text_content},
{
"type": "image_url",
"image_url": {
"url": f"data:image/png;base64,{image_b64}",
},
},
]
return result
# ── Generation (proxy to llama-server) ────────────────────────
def generate_chat_completion(
self,
messages: list[dict],
image_b64: Optional[str] = None,
temperature: float = 0.7,
top_p: float = 0.9,
top_k: int = 40,
min_p: float = 0.0,
max_tokens: Optional[int] = None,
repetition_penalty: float = 1.0,
stop: Optional[list[str]] = None,
cancel_event: Optional[threading.Event] = None,
) -> Generator[str, None, None]:
"""
Send a chat completion request to llama-server and stream tokens back.
Uses /v1/chat/completions — llama-server handles chat template
application and vision (multimodal image_url parts) natively.
Yields cumulative text (matching InferenceBackend's convention).
"""
if not self.is_loaded:
raise RuntimeError("llama-server is not loaded")
openai_messages = self._build_openai_messages(messages, image_b64)
payload = {
"messages": openai_messages,
"stream": True,
"temperature": temperature,
"top_p": top_p,
"top_k": top_k if top_k >= 0 else 0,
"min_p": min_p,
"repeat_penalty": repetition_penalty,
}
if max_tokens is not None:
payload["max_tokens"] = max_tokens
if stop:
payload["stop"] = stop
url = f"{self.base_url}/v1/chat/completions"
cumulative = ""
in_thinking = False
try:
with httpx.Client(timeout = None) as client:
with client.stream("POST", url, json = payload) as response:
if response.status_code != 200:
error_body = response.read().decode()
raise RuntimeError(
f"llama-server returned {response.status_code}: {error_body}"
)
buffer = ""
for raw_chunk in response.iter_text():
if cancel_event is not None and cancel_event.is_set():
break
buffer += raw_chunk
while "\n" in buffer:
line, buffer = buffer.split("\n", 1)
line = line.strip()
if not line:
continue
if line == "data: [DONE]":
if in_thinking:
cumulative += "</think>"
yield cumulative
return
if not line.startswith("data: "):
continue
try:
data = json.loads(line[6:])
choices = data.get("choices", [])
if choices:
delta = choices[0].get("delta", {})
# Handle reasoning/thinking tokens
# llama-server sends these as "reasoning_content"
# Wrap in <think> tags for the frontend parser
reasoning = delta.get("reasoning_content", "")
if reasoning:
if not in_thinking:
cumulative += "<think>"
in_thinking = True
cumulative += reasoning
yield cumulative
token = delta.get("content", "")
if token:
if in_thinking:
cumulative += "</think>"
in_thinking = False
cumulative += token
yield cumulative
except json.JSONDecodeError:
logger.debug(
f"Skipping malformed SSE line: {line[:100]}"
)
except httpx.ConnectError:
raise RuntimeError("Lost connection to llama-server")
except Exception as e:
if cancel_event is not None and cancel_event.is_set():
return
raise
# ── TTS support ────────────────────────────────────────────
def detect_audio_type(self) -> Optional[str]:
"""Detect audio/TTS codec by probing the loaded model's vocabulary."""
if not self.is_loaded:
return None
try:
with httpx.Client(timeout = 10) as client:
def _detok(tid: int) -> str:
r = client.post(
f"{self.base_url}/detokenize", json = {"tokens": [tid]}
)
return r.json().get("content", "") if r.status_code == 200 else ""
def _tok(text: str) -> list[int]:
r = client.post(
f"{self.base_url}/tokenize",
json = {"content": text, "add_special": False},
)
return r.json().get("tokens", []) if r.status_code == 200 else []
# Check codec-specific tokens (not generic ones that may exist in non-audio models)
if "<custom_token_" in _detok(128258) and "<custom_token_" in _detok(
128259
):
return "snac"
if len(_tok("<|AUDIO|>")) == 1 and len(_tok("<|audio_eos|>")) == 1:
return "csm"
if len(_tok("<|startoftranscript|>")) == 1:
return "whisper"
if (
len(_tok("<|bicodec_semantic_0|>")) == 1
and len(_tok("<|bicodec_global_0|>")) == 1
):
return "bicodec"
if len(_tok("<|c1_0|>")) == 1 and len(_tok("<|c2_0|>")) == 1:
return "dac"
except Exception as e:
logger.debug(f"Audio type detection failed: {e}")
return None
# Prompt format per codec: (template, stop_tokens, needs_token_ids)
# Matches prompts in InferenceBackend._generate_snac/bicodec/dac
_TTS_PROMPTS = {
"snac": (
"<custom_token_3>{text}<|eot_id|><custom_token_4>",
["<custom_token_2>"],
True,
),
"bicodec": (
"<|task_tts|><|start_content|>{text}<|end_content|><|start_global_token|>",
["<|im_end|>", "</s>"],
False,
),
"dac": (
"<|im_start|>\n<|text_start|>{text}<|text_end|>\n<|audio_start|><|global_features_start|>\n",
["<|im_end|>", "<|audio_end|>"],
False,
),
}
_codec_mgr = None # Shared AudioCodecManager instance
def init_audio_codec(self, audio_type: str) -> None:
"""Load the audio codec at model load time (mirrors non-GGUF path)."""
import torch
from core.inference.audio_codecs import AudioCodecManager
if LlamaCppBackend._codec_mgr is None:
LlamaCppBackend._codec_mgr = AudioCodecManager()
device = "cuda" if torch.cuda.is_available() else "cpu"
model_repo_path = None
# BiCodec needs a repo with BiCodec/ weights — download canonical SparkTTS
if audio_type == "bicodec":
from huggingface_hub import snapshot_download
import os
repo_path = snapshot_download(
"unsloth/Spark-TTS-0.5B", local_dir = "Spark-TTS-0.5B"
)
model_repo_path = os.path.abspath(repo_path)
LlamaCppBackend._codec_mgr.load_codec(
audio_type, device, model_repo_path = model_repo_path
)
logger.info(f"Loaded audio codec for GGUF TTS: {audio_type}")
def generate_audio_response(
self,
text: str,
audio_type: str,
temperature: float = 0.6,
top_p: float = 0.95,
top_k: int = 50,
min_p: float = 0.0,
max_new_tokens: int = 2048,
repetition_penalty: float = 1.1,
) -> tuple:
"""
Generate TTS audio via llama-server /completion + codec decoding.
Returns (wav_bytes, sample_rate).
"""
if audio_type not in self._TTS_PROMPTS:
raise RuntimeError(f"GGUF TTS does not support '{audio_type}' codec.")
tpl, stop, need_ids = self._TTS_PROMPTS[audio_type]
payload: dict = {
"prompt": tpl.format(text = text),
"stream": False,
"n_predict": max_new_tokens,
"temperature": temperature,
"top_p": top_p,
"top_k": top_k if top_k >= 0 else 0,
"min_p": min_p,
"repeat_penalty": repetition_penalty,
}
if stop:
payload["stop"] = stop
if need_ids:
payload["n_probs"] = 1
with httpx.Client(timeout = httpx.Timeout(300, connect = 10)) as client:
resp = client.post(f"{self.base_url}/completion", json = payload)
if resp.status_code != 200:
raise RuntimeError(
f"llama-server returned {resp.status_code}: {resp.text}"
)
data = resp.json()
token_ids = (
[p["id"] for p in data.get("completion_probabilities", []) if "id" in p]
if need_ids
else None
)
import torch
device = "cuda" if torch.cuda.is_available() else "cpu"
return LlamaCppBackend._codec_mgr.decode(
audio_type, device, token_ids = token_ids, text = data.get("content", "")
)