From d62c957d9a0c8ec6ad2e14dbbb3bda166b2a79a4 Mon Sep 17 00:00:00 2001
From: Tarit Witworrasakul <60599564+wtarit@users.noreply.github.com>
Date: Sun, 5 Apr 2026 06:59:46 -0700
Subject: [PATCH] Update connection pooling

---
 app/database.py | 27 +++++++++++++++++++++++++--
 compose.dev.yml |  7 ++++---
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/app/database.py b/app/database.py
index 593fcce..8ccb5fc 100644
--- a/app/database.py
+++ b/app/database.py
@@ -1,4 +1,6 @@
+import heapq
 import os
+import time
 
 from peewee import DatabaseProxy, Model
 from playhouse.pool import PooledPostgresqlDatabase
@@ -18,11 +20,32 @@ def init_db(app):
         port=int(os.environ.get("DATABASE_PORT", 5432)),
         user=os.environ.get("DATABASE_USER", "postgres"),
         password=os.environ.get("DATABASE_PASSWORD", "postgres"),
-        max_connections=20,
+        max_connections=int(os.environ.get("DATABASE_MAX_CONNECTIONS", 20)),
         stale_timeout=300,
+        timeout=10,
     )
     db.initialize(database)
 
+    # Pre-fill the connection pool so startup traffic doesn't thundering-herd PostgreSQL
+    min_connections = int(os.environ.get("DATABASE_MIN_CONNECTIONS", 10))
+    warm_conns = []
+    for _ in range(min_connections):
+        try:
+            conn = super(PooledPostgresqlDatabase, database)._connect()
+            ts = time.time()
+            database._heap_counter += 1
+            heapq.heappush(database._connections, (ts, database._heap_counter, conn))
+            warm_conns.append(conn)
+        except Exception:
+            break
+
+    pid = os.getpid()
+    app.logger.info(
+        "Connection pool pre-filled: %d/%d connections ready (worker pid=%d, max=%d)",
+        len(warm_conns), min_connections, pid,
+        int(os.environ.get("DATABASE_MAX_CONNECTIONS", 20)),
+    )
+
     @app.before_request
     def _db_connect():
         from flask import request
@@ -31,7 +54,7 @@ def _db_connect():
             return
         db.connect(reuse_if_open=True)
 
-    @app.teardown_appcontext
+    @app.teardown_request
     def _db_close(exc):
         if not db.is_closed():
             db.close()
diff --git a/compose.dev.yml b/compose.dev.yml
index 30ee56a..bae7e90 100644
--- a/compose.dev.yml
+++ b/compose.dev.yml
@@ -1,12 +1,13 @@
 services:
   db:
-    image: postgres:18-alpine
+    image: postgres:18
     environment:
       POSTGRES_DB: hackathon_db
       POSTGRES_USER: postgres
       POSTGRES_PASSWORD: postgres
+    command: ["postgres", "-c", "max_connections=200"]
     volumes:
-      - pgdata_dev:/var/lib/postgresql/data
+      - pgdata_dev:/var/lib/postgresql
     ports:
       - "5432:5432"
     healthcheck:
@@ -16,7 +17,7 @@ services:
       retries: 5
 
   valkey:
-    image: valkey/valkey:8-alpine
+    image: valkey/valkey:8
     ports:
       - "6379:6379"
     healthcheck: