Use connection pool for job enqueueing instead of per-request

- Added get_job_pool() for lazy pool initialization
- Added close_job_pool() for graceful shutdown
- Hooked pool shutdown into FastAPI lifespan
- Reuses connections instead of creating new ones per enqueue

backend/jobs.py

@@ -15,6 +15,25 @@ _raw_url = os.getenv(
 )
 DATABASE_URL = _raw_url.replace("postgresql+asyncpg://", "postgresql://")
 
+# Connection pool for job enqueueing (lazy initialized)
+_pool: asyncpg.Pool | None = None
+
+
+async def get_job_pool() -> asyncpg.Pool:
+    """Get or create the connection pool for job enqueueing."""
+    global _pool
+    if _pool is None:
+        _pool = await asyncpg.create_pool(DATABASE_URL, min_size=1, max_size=5)
+    return _pool
+
+
+async def close_job_pool() -> None:
+    """Close the connection pool. Call on app shutdown."""
+    global _pool
+    if _pool is not None:
+        await _pool.close()
+        _pool = None
+
 
 async def enqueue_random_number_job(user_id: int) -> int:
     """
@@ -29,11 +48,9 @@ async def enqueue_random_number_job(user_id: int) -> int:
     Raises:
         Exception: If enqueueing fails.
     """
-    conn = await asyncpg.connect(DATABASE_URL)
-    try:
+    pool = await get_job_pool()
+    async with pool.acquire() as conn:
         queries = Queries.from_asyncpg_connection(conn)
         payload = json.dumps({"user_id": user_id}).encode()
         job_ids = await queries.enqueue(JOB_RANDOM_NUMBER, payload)
         return job_ids[0]
-    finally:
-        await conn.close()

backend/main.py

@@ -6,6 +6,7 @@ from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from database import Base, engine
+from jobs import close_job_pool
 from routes import audit as audit_routes
 from routes import auth as auth_routes
 from routes import availability as availability_routes
@@ -27,6 +28,8 @@ async def lifespan(app: FastAPI):
     async with engine.begin() as conn:
         await conn.run_sync(Base.metadata.create_all)
     yield
+    # Cleanup on shutdown
+    await close_job_pool()
 
 
 app = FastAPI(lifespan=lifespan)