Disable JIT while doing type introspection (MagicStack#1082)

The misapplication of JIT to asyncpg introspection queries has been a constant source of user complaints. Closes: MagicStack#530 Closes: MagicStack#1078 Previously: MagicStack#875, MagicStack#794, MagicStack#782, MagicStack#741, MagicStack#727 (and probably more).

Author: elprans

asyncpg/connection.py

@@ -461,14 +461,47 @@ async def _get_statement(
  return statement
 
  async def _introspect_types(self, typeoids, timeout):
- return await self.__execute(
+ if self._server_caps.jit:
+ try:
+ cfgrow, _ = await self.__execute(
+ """
+ SELECT
+ current_setting('jit') AS cur,
+ set_config('jit', 'off', false) AS new
+ """,
+ (),
+ 0,
+ timeout,
+ ignore_custom_codec=True,
+ )
+ jit_state = cfgrow[0]['cur']
+ except exceptions.UndefinedObjectError:
+ jit_state = 'off'
+ else:
+ jit_state = 'off'
+
+ result = await self.__execute(
  self._intro_query,
  (list(typeoids),),
  0,
  timeout,
  ignore_custom_codec=True,
  )
 
+ if jit_state != 'off':
+ await self.__execute(
+ """
+ SELECT
+ set_config('jit', $1, false)
+ """,
+ (jit_state,),
+ 0,
+ timeout,
+ ignore_custom_codec=True,
+ )
+
+ return result
+
  async def _introspect_type(self, typename, schema):
  if (
  schema == 'pg_catalog'
@@ -2370,7 +2403,7 @@ class _ConnectionProxy:
 ServerCapabilities = collections.namedtuple(
  'ServerCapabilities',
  ['advisory_locks', 'notifications', 'plpgsql', 'sql_reset',
- 'sql_close_all'])
+ 'sql_close_all', 'jit'])
 ServerCapabilities.__doc__ = 'PostgreSQL server capabilities.'
 
 
@@ -2382,34 +2415,39 @@ def _detect_server_capabilities(server_version, connection_settings):
  plpgsql = False
  sql_reset = True
  sql_close_all = False
+ jit = False
  elif hasattr(connection_settings, 'crdb_version'):
  # CockroachDB detected.
  advisory_locks = False
  notifications = False
  plpgsql = False
  sql_reset = False
  sql_close_all = False
+ jit = False
  elif hasattr(connection_settings, 'crate_version'):
  # CrateDB detected.
  advisory_locks = False
  notifications = False
  plpgsql = False
  sql_reset = False
  sql_close_all = False
+ jit = False
  else:
  # Standard PostgreSQL server assumed.
  advisory_locks = True
  notifications = True
  plpgsql = True
  sql_reset = True
  sql_close_all = True
+ jit = server_version >= (11, 0)
 
  return ServerCapabilities(
  advisory_locks=advisory_locks,
  notifications=notifications,
  plpgsql=plpgsql,
  sql_reset=sql_reset,
- sql_close_all=sql_close_all
+ sql_close_all=sql_close_all,
+ jit=jit,
  )
 
 

tests/test_introspection.py

@@ -43,6 +43,12 @@ def tearDownClass(cls):
 
  super().tearDownClass()
 
+ @classmethod
+ def get_server_settings(cls):
+ settings = super().get_server_settings()
+ settings.pop('jit', None)
+ return settings
+
  def setUp(self):
  super().setUp()
  self.loop.run_until_complete(self._add_custom_codec(self.con))
@@ -124,7 +130,7 @@ async def test_introspection_no_stmt_cache_03(self):
  await self.con.fetchval(
  "SELECT $1::int[], '{foo}'".format(foo='a' * 10000), [1, 2])
 
- self.assertEqual(apg_con._uid, old_uid + 1)
+ self.assertGreater(apg_con._uid, old_uid)
 
  async def test_introspection_sticks_for_ps(self):
  # Test that the introspected codec pipeline for a prepared