Delete expired session files when there is no traffic

Most HTTP requests create a file in the sessions directory. Open browsers
call "/misc/cleanup" every five minutes, but session files can accumulate
after browsers are closed.

Wake periodically to delete expired sessions according to the
CHECK_SESSION_FILES_INTERVAL setting.

Fixes: #1999
Fixes: #8355

Author: cbandy

web/pgadmin/misc/__init__.py

@@ -156,6 +156,20 @@ def register(self, app, options):
         from .workspaces import blueprint as module
         self.submodules.append(module)
 
+        def autovacuum_sessions():
+            import threading
+
+            with app.app_context():
+                cleanup_session_files()
+
+            # repeat every five minutes until exit
+            # https://github.com/python/cpython/issues/98230
+            t = threading.Timer(5 * 60, autovacuum_sessions)
+            t.daemon = True
+            t.start()
+
+        app.register_before_app_start(autovacuum_sessions)
+
         super().register(app, options)