myYouTube/backend/app/services/scheduler.py

import logging

from apscheduler.schedulers.background import BackgroundScheduler

from app.config import settings
from app.db import SessionLocal
from app.services import sync

logger = logging.getLogger(__name__)


def _run_subscriptions_sync() -> None:
    db = SessionLocal()
    try:
        sync.sync_subscriptions(db)
    except sync.SyncInProgress:
        logger.info("Scheduled subscriptions sync skipped: already running")
    except Exception:
        logger.exception("Scheduled subscriptions sync failed")
    finally:
        db.close()


def create_scheduler() -> BackgroundScheduler:
    # Videos sync is not scheduled anymore: it runs on user activity via
    # services.sync_trigger.maybe_trigger_videos_sync (see require_session).
    scheduler = BackgroundScheduler(timezone="UTC")
    scheduler.add_job(
        _run_subscriptions_sync,
        "interval",
        hours=settings.subscriptions_sync_interval_hours,
        id="subscriptions_sync",
    )
    return scheduler