Migrate from psycopg2 to psycopg3 to fix SIGSEGV crashes

Procfile

@@ -1 +1 @@
-web: gunicorn app:app --worker-class gevent --workers=4
+web: gunicorn app:app --workers=4

db.py

@@ -1,7 +1,7 @@
 import os
-import psycopg2
-from psycopg2 import pool
-from psycopg2.extras import RealDictCursor
+import psycopg
+from psycopg_pool import ConnectionPool
+from psycopg.rows import dict_row
 from datetime import datetime
 from dateutil.relativedelta import relativedelta
 from urllib.parse import urlparse
@@ -32,14 +32,11 @@ class DataBase():
             raise Exception("No DATABASE_URL environment variable set")
 
         if DataBase._pool is None:
-            db_url = urlparse(os.environ['DATABASE_URL'])
-            DataBase._pool = pool.ThreadedConnectionPool(
-                1, 20, # minconn, maxconn
-                database=db_url.path[1:],
-                user=db_url.username,
-                password=db_url.password,
-                host=db_url.hostname,
-                port=db_url.port
+            # Note: psycopg3 ConnectionPool takes a conninfo string directly, not parsed kwargs
+            DataBase._pool = ConnectionPool(
+                conninfo=os.environ['DATABASE_URL'],
+                min_size=1,
+                max_size=20
             )
 
     def getDB(self):
@@ -54,7 +51,8 @@ class DataBase():
 
     def execute(self, query, args=(), one=False, commit=False):
         conn = self.getDB()
-        cur = conn.cursor(cursor_factory=RealDictCursor)
+        cur = conn.cursor(row_factory=dict_row)
+        # Convert any custom placeholders from %s to standard %s format used by psycopg3
         cur.execute(query, args)
         rv = None
         if cur.description is not None:

requirements.txt

@@ -1,9 +1,9 @@
 Flask>=3.0.0
 gunicorn>=21.2.0
-gevent>=23.9.1
 Jinja2>=3.1.0
 jinja-partials==0.1.1
-psycopg2-binary>=2.9.9
+psycopg[binary]>=3.0.0
+psycopg_pool>=3.2.0
 flask-htmx>=0.4.0
 python-dateutil==2.8.2
 minify-html==0.10.3