fix(celery): use a lightweight method of db ping to speed up tasks executions

rhodecode/lib/celerylib/utils.py

@@ -116,14 +116,19 b' def parse_ini_vars(ini_vars):'
 
 
 def ping_db():
-    from rhodecode.model import meta
-    from rhodecode.model.db import DbMigrateVersion
     log.info('Testing DB connection...')
 
+    from sqlalchemy import text
+    from rhodecode.model import meta
+    qry = text("SELECT user_id from users where username = :uname")
     for test in range(10):
         try:
-            scalar = DbMigrateVersion.query().scalar()
-            log.debug('DB PING %s@%s', scalar, scalar.version)
+            engine = meta.get_engine()
+            with meta.SA_Session(engine) as session:
+                result = session.execute(qry, {'uname': 'default'})
+                user_id = result.first()[0]
+
+            log.debug('DB PING user_id:%s', user_id)
             break
         except Exception:
             retry = 1