unsloth/studio/backend/routes/training.py
Wasim Yousef Said 208862218d
feat(studio): training history persistence and past runs viewer (#4501)
* feat(db): add SQLite storage layer for training history

* feat(api): add training history endpoints and response models

* feat(training): integrate DB persistence into training event loop

* feat(ui): add training history views and card grid

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fix(studio): address review issues in training history persistence

- Strip hf_token/wandb_token from config before SQLite storage
- Add UUID suffix to job_id for collision resistance
- Use isfinite() for 0.0 metric handling throughout
- Respect _should_stop in error event finalization
- Run schema DDL once per process, not per connection
- Close connection on schema init failure
- Guard cleanup_orphaned_runs at startup
- Cap _metric_buffer at 500 entries
- Make FLUSH_THRESHOLD a class constant
- Map 'running' to 'training' phase in historical view
- Derive LR/GradNorm from history arrays in historical view
- Fix nested button with div[role=button] in history cards
- Guard String(value) against null/undefined in config popover
- Clear selectedHistoryRunId on auto tab switch

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fix(studio): address round-2 review findings across training backend and frontend

Backend (training.py):
- Move state mutation after proc.start() so a failed spawn does not wedge
  the backend with is_training=True
- Create DB run row eagerly after proc.start() so runs appear in history
  during model loading, not after first metric event
- Rewrite _flush_metrics_to_db() with snapshot-before-insert pattern to
  preserve metrics arriving during the write and retain buffer on failure
- Guard eval_loss with float() coercion and math.isfinite(), matching the
  existing grad_norm guard
- Increase pump thread join timeout from 3s to 8s to cover SQLite's
  default 5s lock timeout

Frontend (studio-page.tsx):
- Fix history navigation: check isTrainingRunning instead of
  showTrainingView in onSelectRun so completed runs are not misrouted
- Replace activeTab state + auto-switch useEffect with derived tab to
  eliminate react-hooks/set-state-in-effect lint violation

Frontend (historical-training-view.tsx):
- Add explicit "running" branch to message ternary so running runs no
  longer fall through to "Training errored"
- Derive loading from detail/error state and move cleanup to effect
  return to eliminate react-hooks/set-state-in-effect lint violation

Frontend (progress-section.tsx):
- Derive stopRequested from isTrainingRunning && stopRequestedLocal to
  eliminate react-hooks/set-state-in-effect lint violation and remove
  unused useEffect import

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* fix(studio): resolve 3 remaining bugs from round-2 review

1. Stuck on Current Run tab [12/20]: Only force "current-run" tab when
   isTrainingRunning is true, not when stale completed-run data exists.
   After training ends, users can freely navigate to Configure.

2. Incomplete metric sanitization [7/20]: Apply float() coercion and
   isfinite() guards to loss and learning_rate, matching the existing
   pattern used by grad_norm and eval_loss. Prevents TypeError from
   string values and NaN leaks into history arrays.

3. Stop button state leak across runs [10/20]: Add key={runtime.jobId}
   to ProgressSection so React remounts it when a new run starts,
   resetting stopRequestedLocal state.

* fix(studio): deduplicate loss/lr sanitization in training event handler

Reuse _safe_loss/_safe_lr from the progress update block instead of
re-sanitizing the same raw event values for metric history.

* fix(studio): restore loss > 0 guard to prevent eval steps injecting 0.0 into metric histories

Round-2/3 fixes relaxed the history append guard from `loss > 0` to
`loss is not None`, which let eval-only log events (where loss defaults
to 0.0) append fake zeros into loss_history and lr_history. Restore the
`loss > 0` check to match the worker's own has_train_loss gate. The
float() coercion and isfinite() sanitization from round-3 remain intact.

* fix(studio): resolve training history bugs — nullable loss/lr, tab nav, sparkline

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Daniel Han <danielhanchen@gmail.com>
2026-03-25 00:58:55 -07:00

844 lines
33 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 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 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 GPU utilization %, temperature, VRAM usage, and power draw
via nvidia-smi for maximum accuracy.
"""
from utils.hardware import get_gpu_utilization
return get_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.
"""
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"
)
# 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,
"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,
"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 "",
"trust_remote_code": request.trust_remote_code,
}
# 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
# Free GPU memory: shut down any running inference/export subprocesses
# before training starts (they'd compete for VRAM otherwise)
try:
from core.inference import get_inference_backend
inf_backend = get_inference_backend()
if inf_backend.active_model_name:
logger.info(
"Unloading inference model '%s' to free GPU memory for training",
inf_backend.active_model_name,
)
inf_backend._shutdown_subprocess()
inf_backend.active_model_name = None
inf_backend.models.clear()
except Exception as e:
logger.warning("Could not unload inference model: %s", e)
try:
from core.export import get_export_backend
exp_backend = get_export_backend()
if exp_backend.current_checkpoint:
logger.info(
"Shutting down export subprocess to free GPU memory for training"
)
exp_backend._shutdown_subprocess()
exp_backend.current_checkpoint = None
exp_backend.is_vision = False
exp_backend.is_peft = False
except Exception as e:
logger.warning("Could not shut down export subprocess: %s", e)
# 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 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)}",
)
@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),
}
# 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",
},
)