unsloth/studio/backend/routes/training.py
Daniel Han-Chen cae37123c9 Fix/adjust diffusion: round 30 follow-up P1 batch for PR #5754
Addresses remaining round-30 reviewer findings against PR #5754
(diffusion image generation in Unsloth Studio). The studio.txt /
constraints.txt / colab-new hub-bump items (round 30 #1-#3) are
intentionally skipped: the live B200 Studio install path with
huggingface_hub==0.36.2, transformers==4.57.6 and diffusers==0.37.1
imports Flux2KleinPipeline cleanly and runs end-to-end image
generation (see staging CI green on bec81b88 plus round 28-30
local validation suites). The is_offline_mode ImportError the
reviewer cites only triggers with transformers 5.x against
huggingface_hub 0.x; the constraints pin holds transformers at 4.x
so the combo never materialises on the standard install path.

Concurrency: close the helper / advisor GPU-start race in all four
public load paths (round 30 P1 #7-#10).
  * Add a _PUBLIC_LOAD_PENDING_COUNT counter in
    utils/datasets/llm_assist.py, published under
    _HELPER_ADVISOR_START_LOCK by _raise_if_helper_advisor_busy and
    cleared by a paired _clear_public_load_window in
    routes/inference.py. A concurrent helper / advisor start now
    sees public_load_pending() inside _gpu_workload_busy_for_helper
    and refuses VRAM until the public load attempt finishes,
    closing the window between the busy snapshot and the public
    load flipping its public ownership flags (is_loaded,
    current_checkpoint, is_training_active, etc.).
  * Wire the paired clear into all five call sites (GGUF chat,
    safetensors chat, diffusion image load, training start, export
    load-checkpoint). The chat path tracks the published tag in a
    local so the finally clears the same counter on either branch
    or on early HTTPException.

Security: gate /api/inference/images/load against arbitrary
local-path probes (round 30 P1 #4). Mirror the chat
/api/inference/load native_path_lease boundary so an authenticated
session cannot use repo_id or base_repo as a directory probe.
  * Add native_path_lease + base_repo_native_path_lease to
    DiffusionLoadRequest (optional; Hub ids skip the lease).
  * Add _looks_like_local_diffusion_path + a
    _resolve_diffusion_repo_for_request helper that requires a
    verified directory-typed native path grant for any value that
    starts with /, ~, ./, ../, contains a backslash, or expands to
    an absolute path. The detector deliberately avoids Path.exists
    so the route does not side-channel filesystem layout via
    differential error messages.

Frontend: split the Images page status fetch from the spinner
toggle (round 30 P2 #12). The mount effect and the is_loading
auto-poll now call a setState-free fetchAndUpdateStatus; the
user-driven Refresh button still calls refreshStatus to flip the
spinner. Cleaner separation than the queueMicrotask shim from the
prior commit; the eslint react-hooks/set-state-in-effect rule is
not in the studio-frontend-ci typecheck gate, and the codebase
already has hundreds of pre-existing violations of the same rule.

98 targeted backend tests pass (test_diffusion_routes,
test_diffusion_backend, test_inference_model_validation,
test_models_get_model_config_case_resolution, test_data_recipe_seed,
test_training_raw_support, test_export_log_cursor). Frontend
typecheck passes.
2026-05-25 15:30:58 +00:00

932 lines
37 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
"""
Training API routes
"""
import sys
from pathlib import Path
from fastapi import APIRouter, Depends, HTTPException, Request
from fastapi.responses import StreamingResponse
from typing import Dict, Optional, Any
import structlog
from loggers import get_logger
import asyncio
from datetime import datetime
import uuid as _uuid
# Add backend directory to path
# The backend code should be in the same directory structure
backend_path = Path(__file__).parent.parent.parent
if str(backend_path) not in sys.path:
sys.path.insert(0, str(backend_path))
# Import backend functions
try:
from core.training import get_training_backend
from core.training.resume import (
can_resume_run,
get_resume_checkpoint_path,
normalize_resume_output_dir,
)
from storage.studio_db import get_resumable_run_by_output_dir
from utils.models.model_config import load_model_defaults
from utils.paths import resolve_dataset_path
except ImportError:
# Fallback: try to import from parent directory
parent_backend = backend_path.parent / "backend"
if str(parent_backend) not in sys.path:
sys.path.insert(0, str(parent_backend))
from core.training import get_training_backend
from core.training.resume import (
can_resume_run,
get_resume_checkpoint_path,
normalize_resume_output_dir,
)
from storage.studio_db import get_resumable_run_by_output_dir
from utils.models.model_config import load_model_defaults
from utils.paths import resolve_dataset_path
# Auth
from auth.authentication import get_current_subject
from models import (
TrainingStartRequest,
TrainingJobResponse,
TrainingStatus,
TrainingProgress,
)
from models.responses import TrainingStopResponse, TrainingMetricsResponse
from pydantic import BaseModel as PydanticBaseModel
class TrainingStopRequest(PydanticBaseModel):
save: bool = True
router = APIRouter()
logger = get_logger(__name__)
def _validate_local_dataset_paths(
paths: list[str], label: str = "Local dataset"
) -> list[str]:
"""Resolve and validate a list of local dataset paths. Returns validated absolute paths."""
validated = []
missing = []
for dataset_path in paths:
dataset_file = resolve_dataset_path(dataset_path)
if not dataset_file.exists():
missing.append(f"{dataset_path} (resolved: {dataset_file})")
continue
logger.info(f"Found {label.lower()} file: {dataset_file}")
validated.append(str(dataset_file))
if missing:
missing_detail = "; ".join(missing[:3])
raise HTTPException(
status_code = 400,
detail = f"{label} not found: {missing_detail}",
)
return validated
@router.get("/hardware")
async def get_hardware_utilization(
current_subject: str = Depends(get_current_subject),
):
"""
Get a live snapshot of GPU hardware utilization.
Designed to be polled by the frontend during training.
Returns live GPU memory usage information for the active backend.
"""
from utils.hardware import get_gpu_utilization
return get_gpu_utilization()
@router.get("/hardware/visible")
async def get_visible_hardware_utilization(
current_subject: str = Depends(get_current_subject),
):
from utils.hardware import get_visible_gpu_utilization
return get_visible_gpu_utilization()
@router.post("/start")
async def start_training(
request: TrainingStartRequest,
current_subject: str = Depends(get_current_subject),
):
"""
Start a training job.
This endpoint initiates training in the background and returns immediately.
Use the /status endpoint to check training progress.
"""
# Round 30 P1 #7: track whether we published a public-load pending
# entry so the outer finally clears it on either success or
# failure (including any early HTTPException raised by the helper
# check itself).
training_load_window_published = False
try:
logger.info(f"Starting training job with model: {request.model_name}")
# NOTE: No in-process ensure_transformers_version() call here.
# The subprocess (worker.py) activates the correct version in a
# fresh Python interpreter before importing any ML libraries.
backend = get_training_backend()
# Check if training is already active (before mutating any state)
if backend.is_training_active():
existing_job_id: Optional[str] = getattr(backend, "current_job_id", "")
return TrainingJobResponse(
job_id = existing_job_id or "",
status = "error",
message = (
"Training is already in progress. "
"Stop current training before starting a new one."
),
error = "Training already active",
)
# Generate job ID — passed into start_training() which sets it on the
# backend only after confirming the old pump thread is dead.
job_id = (
f"job_{datetime.now().strftime('%Y%m%d_%H%M%S')}_{_uuid.uuid4().hex[:8]}"
)
# Validate dataset paths if provided
if request.local_datasets:
request.local_datasets = _validate_local_dataset_paths(
request.local_datasets, "Local dataset"
)
if request.local_eval_datasets and request.eval_steps > 0:
request.local_eval_datasets = _validate_local_dataset_paths(
request.local_eval_datasets, "Local eval dataset"
)
resume_output_dir: Optional[str] = None
if request.resume_from_checkpoint:
try:
resume_output_dir = normalize_resume_output_dir(
request.resume_from_checkpoint
)
except ValueError as e:
raise HTTPException(status_code = 400, detail = str(e))
resume_run = get_resumable_run_by_output_dir(resume_output_dir)
if not resume_run or not can_resume_run(resume_run):
raise HTTPException(
status_code = 400,
detail = "Resume checkpoint must belong to a stopped run with saved trainer state.",
)
resume_checkpoint = get_resume_checkpoint_path(resume_output_dir)
if not resume_checkpoint:
raise HTTPException(
status_code = 400,
detail = "Resume checkpoint must include saved trainer state.",
)
request.resume_from_checkpoint = resume_checkpoint
# Convert request to kwargs for backend
training_kwargs = {
"model_name": request.model_name,
"training_type": request.training_type,
"hf_token": request.hf_token or "",
"load_in_4bit": request.load_in_4bit,
"max_seq_length": request.max_seq_length,
"hf_dataset": request.hf_dataset or "",
"local_datasets": request.local_datasets,
"local_eval_datasets": request.local_eval_datasets,
"format_type": request.format_type,
"subset": request.subset,
"train_split": request.train_split,
"eval_split": request.eval_split,
"eval_steps": request.eval_steps,
"dataset_slice_start": request.dataset_slice_start,
"dataset_slice_end": request.dataset_slice_end,
"custom_format_mapping": request.custom_format_mapping,
"num_epochs": request.num_epochs,
"learning_rate": request.learning_rate,
"embedding_learning_rate": request.embedding_learning_rate,
"batch_size": request.batch_size,
"gradient_accumulation_steps": request.gradient_accumulation_steps,
"warmup_steps": request.warmup_steps,
"warmup_ratio": request.warmup_ratio,
"max_steps": request.max_steps,
"save_steps": request.save_steps,
"weight_decay": request.weight_decay,
"max_grad_norm": request.max_grad_norm,
"random_seed": request.random_seed,
"packing": request.packing,
"optim": request.optim,
"lr_scheduler_type": request.lr_scheduler_type,
"use_lora": request.use_lora,
"lora_r": request.lora_r,
"lora_alpha": request.lora_alpha,
"lora_dropout": request.lora_dropout,
"target_modules": request.target_modules
if request.target_modules
else None,
"gradient_checkpointing": request.gradient_checkpointing.strip()
if request.gradient_checkpointing and request.gradient_checkpointing.strip()
else "unsloth",
"use_rslora": request.use_rslora,
"use_loftq": request.use_loftq,
"train_on_completions": request.train_on_completions,
"finetune_vision_layers": request.finetune_vision_layers,
"finetune_language_layers": request.finetune_language_layers,
"finetune_attention_modules": request.finetune_attention_modules,
"finetune_mlp_modules": request.finetune_mlp_modules,
"is_dataset_image": request.is_dataset_image,
"is_dataset_audio": request.is_dataset_audio,
"is_embedding": request.is_embedding,
"enable_wandb": request.enable_wandb,
"wandb_token": request.wandb_token or "",
"wandb_project": request.wandb_project or "",
"enable_tensorboard": request.enable_tensorboard,
"tensorboard_dir": request.tensorboard_dir or "",
"output_dir": resume_output_dir,
"resume_from_checkpoint": request.resume_from_checkpoint,
"trust_remote_code": request.trust_remote_code,
"gpu_ids": request.gpu_ids,
}
# Training page has no trust_remote_code toggle — the value comes from
# YAML model defaults applied when the user selects a model. As a safety
# net, consult the YAML directly so models that need it always get it.
if not training_kwargs["trust_remote_code"]:
model_defaults = load_model_defaults(request.model_name)
yaml_trust = model_defaults.get("training", {}).get(
"trust_remote_code", False
)
if yaml_trust:
logger.info(
f"YAML config sets trust_remote_code=True for {request.model_name}"
)
training_kwargs["trust_remote_code"] = True
# Symmetric lifecycle guard: refuse to start training while
# an export job is in flight. Round 10 review #1 -- the
# previous code went straight to ``_release_export_for``,
# which would terminate the in-flight export and corrupt
# the user's output artifact. Now we 409 first; the user
# stops the export and re-submits.
from routes.inference import (
_clear_public_load_window,
_raise_if_export_active,
_raise_if_helper_advisor_busy,
_release_chat_for,
_release_diffusion_for,
_release_export_for,
)
_raise_if_export_active("training")
# Round 28 P1 #5: refuse before any release fires so AI Assist
# busy does not first tear down idle diffusion/export.
# Round 30 P1 #7: also publishes a public-load pending entry so
# a concurrent helper / advisor start cannot win the start
# lock between our snapshot and start_training flipping
# is_training_active. Paired clear lives in the outer
# ``finally`` below.
_raise_if_helper_advisor_busy("training")
training_load_window_published = True
# Round 18 P1 #8: release settled export FIRST so an export
# cleanup failure preserves the user's currently loaded chat
# model. The previous order (chat -> export) would drop chat
# and then refuse training when a wedged idle export raised,
# leaving the user with nothing loaded.
# Round 24 P1 #2: same reasoning extended to diffusion ->
# chat. A wedged diffusion unload used to fire AFTER the chat
# backend was already gone, so the user lost both chat and
# diffusion on a single failure mode. Order is now
# export -> diffusion -> chat, with chat as the last drop so
# earlier failures preserve it.
await _release_export_for("training")
await _release_diffusion_for("training")
await _release_chat_for("training")
# (Diffusion release moved above chat in round 24 P1 #2;
# the old trailing call was removed to avoid double-unload.)
# start_training now spawns a subprocess (non-blocking)
success = backend.start_training(job_id = job_id, **training_kwargs)
if not success:
progress_error = backend.trainer.training_progress.error
return TrainingJobResponse(
job_id = backend.current_job_id or "",
status = "error",
message = progress_error or "Failed to start training subprocess",
error = progress_error or "subprocess_start_failed",
)
return TrainingJobResponse(
job_id = job_id,
status = "queued",
message = "Training job queued and starting in subprocess",
error = None,
)
except ValueError as e:
logger.warning("Rejected training GPU selection: %s", e)
raise HTTPException(status_code = 400, detail = str(e))
except HTTPException:
# Preserve the intended status code from
# _raise_if_training_active / _raise_if_export_active
# (409) and the gpu-id 400 raises above. Without this
# explicit re-raise the broad ``except Exception`` below
# converts a deliberate 409 into a 500.
raise
except Exception as e:
logger.error(f"Error starting training: {e}", exc_info = True)
raise HTTPException(
status_code = 500,
detail = f"Failed to start training: {str(e)}",
)
finally:
# Round 30 P1 #7: clear the public-load pending entry once the
# start attempt has finished. Skipped when the helper-busy
# check itself raised (no publish to clear) so the counter
# stays in sync with publishes.
if training_load_window_published:
try:
from routes.inference import _clear_public_load_window
except Exception:
pass
else:
_clear_public_load_window("training")
@router.post("/stop", response_model = TrainingStopResponse)
async def stop_training(
body: TrainingStopRequest = TrainingStopRequest(),
current_subject: str = Depends(get_current_subject),
):
"""
Stop the currently running training job.
Body:
save (bool): If True (default), save the model at the current checkpoint.
"""
try:
backend = get_training_backend()
is_active = backend.is_training_active()
logger.info("Stop requested: save=%s is_active=%s", body.save, is_active)
if not is_active:
return TrainingStopResponse(
status = "idle", message = "No training job is currently running"
)
# Call backend stop method
backend.stop_training(save = body.save)
return TrainingStopResponse(
status = "stopped",
message = "Stop requested. Training will stop at the next safe step.",
)
except Exception as e:
logger.error(f"Error stopping training: {e}", exc_info = True)
raise HTTPException(
status_code = 500, detail = f"Failed to stop training: {str(e)}"
)
@router.post("/reset")
async def reset_training(
current_subject: str = Depends(get_current_subject),
):
"""
Reset training state so the user can return to configuration.
"""
try:
backend = get_training_backend()
is_active = backend.is_training_active()
if is_active:
if backend._cancel_requested:
# Cancel (save=False) was requested — force-terminate so we can reset immediately
logger.info(
"Force-terminating subprocess for immediate reset (cancel path)"
)
backend.force_terminate()
else:
logger.warning(
"Rejected reset while training active: is_active=%s", is_active
)
raise HTTPException(
status_code = 409,
detail = "Training is still running. Stop training and wait for it to finish before resetting.",
)
logger.info("Reset training state: clearing runtime + metric history")
backend._should_stop = False # Clear stop flag so status returns to idle
backend.trainer._update_progress(
is_training = False,
is_completed = False,
error = None,
status_message = "Ready to train",
step = 0,
loss = None,
epoch = 0,
total_steps = 0,
)
backend.loss_history = []
backend.lr_history = []
backend.step_history = []
backend.grad_norm_history = []
backend.grad_norm_step_history = []
return {"status": "ok"}
except HTTPException:
raise
except Exception as e:
logger.error(f"Error resetting training: {e}", exc_info = True)
raise HTTPException(
status_code = 500,
detail = f"Failed to reset training: {str(e)}",
)
@router.get("/status")
async def get_training_status(
current_subject: str = Depends(get_current_subject),
):
"""
Get the current training status.
"""
try:
backend = get_training_backend()
job_id: str = getattr(backend, "current_job_id", "") or ""
# Check if training is active
is_active = backend.is_training_active()
# Get progress info from trainer
try:
progress = backend.trainer.get_training_progress()
except Exception:
progress = None
status_message = (
getattr(progress, "status_message", None) if progress else None
) or "Ready to train"
error_message = getattr(progress, "error", None) if progress else None
# Check if training was stopped by user
trainer_stopped = getattr(backend, "_should_stop", False)
# Derive high-level phase
if error_message:
phase = "error"
elif is_active:
msg_lower = status_message.lower()
if "loading" in msg_lower or "importing" in msg_lower:
phase = "loading_model"
elif any(
k in msg_lower for k in ["preparing", "initializing", "configuring"]
):
phase = "configuring"
else:
phase = "training"
elif trainer_stopped:
phase = "stopped"
elif progress and getattr(progress, "is_completed", False):
phase = "completed"
else:
phase = "idle"
details = None
if progress:
details = {
"epoch": getattr(progress, "epoch", 0),
"step": getattr(progress, "step", 0),
"total_steps": getattr(progress, "total_steps", 0),
"loss": getattr(progress, "loss", None),
"learning_rate": getattr(progress, "learning_rate", None),
}
output_dir = getattr(backend, "_output_dir", None)
if output_dir:
details["output_dir"] = output_dir
# Build metric history for chart recovery after SSE reconnection
metric_history = None
if backend.step_history:
metric_history = {
"steps": list(backend.step_history),
"loss": list(backend.loss_history),
"lr": list(backend.lr_history),
"grad_norm": list(getattr(backend, "grad_norm_history", [])),
"grad_norm_steps": list(getattr(backend, "grad_norm_step_history", [])),
"eval_loss": list(backend.eval_loss_history),
"eval_steps": list(backend.eval_step_history),
}
return TrainingStatus(
job_id = job_id,
phase = phase,
is_training_running = is_active,
eval_enabled = backend.eval_enabled,
message = status_message,
error = error_message,
details = details,
metric_history = metric_history,
)
except Exception as e:
logger.error(f"Error getting training status: {e}", exc_info = True)
raise HTTPException(
status_code = 500, detail = f"Failed to get training status: {str(e)}"
)
@router.get("/metrics", response_model = TrainingMetricsResponse)
async def get_training_metrics(
current_subject: str = Depends(get_current_subject),
):
"""
Get training metrics (loss, learning rate, steps).
"""
try:
backend = get_training_backend()
# Get metrics from backend
loss_history = backend.loss_history
lr_history = backend.lr_history
step_history = backend.step_history
grad_norm_history = getattr(backend, "grad_norm_history", [])
grad_norm_step_history = getattr(backend, "grad_norm_step_history", [])
# Get current values
current_loss = loss_history[-1] if loss_history else None
current_lr = lr_history[-1] if lr_history else None
current_step = step_history[-1] if step_history else None
return TrainingMetricsResponse(
loss_history = loss_history,
lr_history = lr_history,
step_history = step_history,
grad_norm_history = grad_norm_history,
grad_norm_step_history = grad_norm_step_history,
current_loss = current_loss,
current_lr = current_lr,
current_step = current_step,
)
except Exception as e:
logger.error(f"Error getting training metrics: {e}", exc_info = True)
raise HTTPException(
status_code = 500, detail = f"Failed to get training metrics: {str(e)}"
)
@router.get("/progress")
async def stream_training_progress(
request: Request,
current_subject: str = Depends(get_current_subject),
):
"""
Stream training progress updates using Server-Sent Events (SSE).
This endpoint provides real-time updates on training progress.
Supports reconnection via the SSE spec:
- Sends `id:` with each event so the browser tracks position.
- Sends `retry:` to control reconnection interval.
- Sends named `event:` types (progress, heartbeat, complete, error).
- Reads `Last-Event-ID` header on reconnect to replay missed steps.
"""
# Read Last-Event-ID header for reconnection resume
last_event_id = request.headers.get("last-event-id")
resume_from_step: Optional[int] = None
if last_event_id is not None:
try:
resume_from_step = int(last_event_id)
logger.info(f"SSE reconnect: resuming from step {resume_from_step}")
except ValueError:
logger.warning(f"Invalid Last-Event-ID: {last_event_id}")
async def event_generator():
backend = get_training_backend()
job_id: str = getattr(backend, "current_job_id", "") or ""
# ── Helpers ──────────────────────────────────────────────
def build_progress(
step: int,
loss: Optional[float],
learning_rate: Optional[float],
total_steps: int,
epoch: Optional[float] = None,
progress: Optional[Any] = None,
grad_norm_override: Optional[float] = None,
eval_loss_override: Optional[float] = None,
) -> TrainingProgress:
total = max(total_steps, 0)
if step < 0 or total == 0:
progress_percent = 0.0
else:
progress_percent = (
float(step) / float(total) * 100.0 if total > 0 else 0.0
)
# Get actual values from progress object if available
elapsed_seconds = (
getattr(progress, "elapsed_seconds", None) if progress else None
)
eta_seconds = getattr(progress, "eta_seconds", None) if progress else None
grad_norm = grad_norm_override
if grad_norm is None and progress:
grad_norm = getattr(progress, "grad_norm", None)
num_tokens = getattr(progress, "num_tokens", None) if progress else None
eval_loss = eval_loss_override
if eval_loss is None and progress:
eval_loss = getattr(progress, "eval_loss", None)
return TrainingProgress(
job_id = job_id,
step = step,
total_steps = total,
loss = loss,
learning_rate = learning_rate,
progress_percent = progress_percent,
epoch = epoch,
elapsed_seconds = elapsed_seconds,
eta_seconds = eta_seconds,
grad_norm = grad_norm,
num_tokens = num_tokens,
eval_loss = eval_loss,
)
def format_sse(
data: str,
event: str = "progress",
event_id: Optional[int] = None,
) -> str:
"""Format a single SSE message with id/event/data fields."""
lines = []
if event_id is not None:
lines.append(f"id: {event_id}")
lines.append(f"event: {event}")
lines.append(f"data: {data}")
lines.append("") # trailing blank line
lines.append("") # double newline terminates the event
return "\n".join(lines)
# ── Retry directive ──────────────────────────────────────
# Tell the browser to reconnect after 3 seconds if the connection drops
yield "retry: 3000\n\n"
# ── Replay missed steps on reconnect ─────────────────────
if resume_from_step is not None and backend.step_history:
replayed = 0
grad_norm_by_step = {
step_val: grad_val
for step_val, grad_val in zip(
getattr(backend, "grad_norm_step_history", []),
getattr(backend, "grad_norm_history", []),
)
}
for i, step_val in enumerate(backend.step_history):
if step_val > resume_from_step:
loss_val = (
backend.loss_history[i]
if i < len(backend.loss_history)
else None
)
lr_val = (
backend.lr_history[i] if i < len(backend.lr_history) else None
)
tp_replay = getattr(
getattr(backend, "trainer", None), "training_progress", None
)
total_replay = (
getattr(tp_replay, "total_steps", step_val)
if tp_replay
else step_val
)
epoch_replay = (
getattr(tp_replay, "epoch", None) if tp_replay else None
)
payload = build_progress(
step_val,
loss_val,
lr_val,
total_replay,
epoch_replay,
progress = tp_replay,
grad_norm_override = grad_norm_by_step.get(step_val),
)
yield format_sse(
payload.model_dump_json(), event = "progress", event_id = step_val
)
replayed += 1
if replayed:
logger.info(f"SSE reconnect: replayed {replayed} missed steps")
# ── Initial status (only on fresh connections) ───────────
if resume_from_step is None:
is_active = backend.is_training_active()
tp = getattr(getattr(backend, "trainer", None), "training_progress", None)
initial_total_steps = getattr(tp, "total_steps", 0) if tp else 0
initial_epoch = getattr(tp, "epoch", None) if tp else None
initial_progress = build_progress(
step = 0,
loss = None,
learning_rate = None,
total_steps = initial_total_steps,
epoch = initial_epoch,
progress = tp,
)
yield format_sse(
initial_progress.model_dump_json(), event = "progress", event_id = 0
)
# If not active, send final state and exit
if not is_active:
if backend.step_history:
final_step = backend.step_history[-1]
final_loss = (
backend.loss_history[-1] if backend.loss_history else None
)
final_lr = backend.lr_history[-1] if backend.lr_history else None
final_total_steps = (
getattr(tp, "total_steps", final_step) if tp else final_step
)
final_epoch = getattr(tp, "epoch", None) if tp else None
payload = build_progress(
final_step,
final_loss,
final_lr,
final_total_steps,
final_epoch,
progress = tp,
)
yield format_sse(
payload.model_dump_json(), event = "complete", event_id = final_step
)
else:
yield format_sse(
build_progress(
-1, None, None, 0, progress = tp
).model_dump_json(),
event = "complete",
event_id = 0,
)
return
# ── Live polling loop ────────────────────────────────────
last_step = resume_from_step if resume_from_step is not None else -1
no_update_count = 0
max_no_updates = (
1800 # Timeout after 30 minutes (large models need time for compilation)
)
while backend.is_training_active():
try:
if backend.step_history:
current_step = backend.step_history[-1]
current_loss = (
backend.loss_history[-1] if backend.loss_history else None
)
current_lr = backend.lr_history[-1] if backend.lr_history else None
tp_inner = getattr(
getattr(backend, "trainer", None), "training_progress", None
)
current_total_steps = (
getattr(tp_inner, "total_steps", current_step)
if tp_inner
else current_step
)
current_epoch = (
getattr(tp_inner, "epoch", None) if tp_inner else None
)
# Only send if step changed
if current_step != last_step:
progress_payload = build_progress(
current_step,
current_loss,
current_lr,
current_total_steps,
current_epoch,
progress = tp_inner,
)
yield format_sse(
progress_payload.model_dump_json(),
event = "progress",
event_id = current_step,
)
last_step = current_step
no_update_count = 0
else:
no_update_count += 1
# Send heartbeat every 10 seconds
if no_update_count % 10 == 0:
heartbeat_payload = build_progress(
current_step,
current_loss,
current_lr,
current_total_steps,
current_epoch,
progress = tp_inner,
)
yield format_sse(
heartbeat_payload.model_dump_json(),
event = "heartbeat",
event_id = current_step,
)
else:
# No steps yet, but training is active (model loading, etc.)
no_update_count += 1
if no_update_count % 5 == 0:
# Pull total_steps and status from trainer so
# the frontend can show "Tokenizing…" etc.
tp_prep = getattr(
getattr(backend, "trainer", None),
"training_progress",
None,
)
prep_total = (
getattr(tp_prep, "total_steps", 0) if tp_prep else 0
)
preparing_payload = build_progress(
0,
None,
None,
prep_total,
progress = tp_prep,
)
yield format_sse(
preparing_payload.model_dump_json(),
event = "heartbeat",
event_id = 0,
)
# Timeout check
if no_update_count > max_no_updates:
logger.warning("Progress stream timeout - no updates received")
tp_timeout = getattr(
getattr(backend, "trainer", None), "training_progress", None
)
timeout_payload = build_progress(
last_step, None, None, 0, progress = tp_timeout
)
yield format_sse(
timeout_payload.model_dump_json(),
event = "error",
event_id = last_step if last_step >= 0 else 0,
)
break
await asyncio.sleep(1) # Poll every second
except Exception as e:
logger.error(f"Error in progress stream: {e}", exc_info = True)
tp_error = getattr(
getattr(backend, "trainer", None), "training_progress", None
)
error_payload = build_progress(0, None, None, 0, progress = tp_error)
yield format_sse(
error_payload.model_dump_json(),
event = "error",
event_id = last_step if last_step >= 0 else 0,
)
break
# ── Final "complete" event ───────────────────────────────
final_step = backend.step_history[-1] if backend.step_history else last_step
final_loss = backend.loss_history[-1] if backend.loss_history else None
final_lr = backend.lr_history[-1] if backend.lr_history else None
final_tp = getattr(getattr(backend, "trainer", None), "training_progress", None)
final_total_steps = (
getattr(final_tp, "total_steps", final_step) if final_tp else final_step
)
final_epoch = getattr(final_tp, "epoch", None) if final_tp else None
final_payload = build_progress(
final_step,
final_loss,
final_lr,
final_total_steps,
final_epoch,
progress = final_tp,
)
yield format_sse(
final_payload.model_dump_json(),
event = "complete",
event_id = final_step if final_step >= 0 else 0,
)
return StreamingResponse(
event_generator(),
media_type = "text/event-stream",
headers = {
"Cache-Control": "no-cache",
"Connection": "keep-alive",
"X-Accel-Buffering": "no",
},
)