update db connection handling

app.py

@@ -2,20 +2,26 @@ import gradio as gr
 from sentence_transformers import SentenceTransformer
 import psycopg2
 import os
+import torch
 
 conn_string = os.environ.get("DATABASE_URL")
-conn = psycopg2.connect(conn_string)
-cur = conn.cursor()
 
 model = SentenceTransformer("multilingual-e5-small", device="cpu")
+model.eval()
 
 def search(query, top_k):
-    query_embedding = model.encode("query: " + query)
-    
+
+    with torch.no_grad():
+        query_embedding = model.encode("query: " + query)
+
+    conn = psycopg2.connect(conn_string)
+    cur = conn.cursor()
+
     query_sql = f"SELECT source_file, chunk FROM items ORDER BY embedding <=> '{str(query_embedding.tolist())}' LIMIT {int(top_k)};"
 
     cur.execute(query_sql)
     results = cur.fetchall()
+    conn.close()
 
     results_format = "\n".join([f"{i+1}. {text} __({file})__" for i, (file, text) in enumerate(results)])