* bpo-31970: Reduce performance overhead of asyncio debug mode.
handler is set, and can be called by a custom exception
handler that wants to defer to the default behavior.
+ This default handler logs the error message and other
+ context-dependent information. In debug mode, a truncated
+ stack trace is also appended showing where the given object
+ (e.g. a handle or future or task) was created, if any.
+
The context parameter has the same meaning as in
`call_exception_handler()`.
"""
# Seconds to wait before retrying accept().
ACCEPT_RETRY_DELAY = 1
+
+# Number of stack entries to capture in debug mode.
+# The large the number, the slower the operation in debug mode
+# (see extract_stack() in events.py)
+DEBUG_STACK_DEPTH = 10
import types
from . import compat
+from . import constants
from . import events
from . import base_futures
from .log import logger
assert inspect.isgenerator(gen) or inspect.iscoroutine(gen), gen
self.gen = gen
self.func = func # Used to unwrap @coroutine decorator
- self._source_traceback = traceback.extract_stack(sys._getframe(1))
+ self._source_traceback = events.extract_stack(sys._getframe(1))
self.__name__ = getattr(gen, '__name__', None)
self.__qualname__ = getattr(gen, '__qualname__', None)
tb = getattr(self, '_source_traceback', ())
if tb:
tb = ''.join(traceback.format_list(tb))
- msg += ('\nCoroutine object created at '
- '(most recent call last):\n')
+ msg += (f'\nCoroutine object created at '
+ f'(most recent call last, truncated to '
+ f'{constants.DEBUG_STACK_DEPTH} last lines):\n')
msg += tb.rstrip()
logger.error(msg)
import threading
import traceback
+from . import constants
+
def _get_function_source(func):
func = inspect.unwrap(func)
return func_repr
+def extract_stack(f=None, limit=None):
+ """Replacement for traceback.extract_stack() that only does the
+ necessary work for asyncio debug mode.
+ """
+ if f is None:
+ f = sys._getframe().f_back
+ if limit is None:
+ # Limit the amount of work to a reasonable amount, as extract_stack()
+ # can be called for each coroutine and future in debug mode.
+ limit = constants.DEBUG_STACK_DEPTH
+ stack = traceback.StackSummary.extract(traceback.walk_stack(f),
+ limit=limit,
+ lookup_lines=False)
+ stack.reverse()
+ return stack
+
+
class Handle:
"""Object returned by callback registration methods."""
self._cancelled = False
self._repr = None
if self._loop.get_debug():
- self._source_traceback = traceback.extract_stack(sys._getframe(1))
+ self._source_traceback = extract_stack(sys._getframe(1))
else:
self._source_traceback = None
self._loop = loop
self._callbacks = []
if self._loop.get_debug():
- self._source_traceback = traceback.extract_stack(sys._getframe(1))
+ self._source_traceback = events.extract_stack(sys._getframe(1))
_repr_info = base_futures._future_repr_info
regex = (r'^<CoroWrapper %s\(?\)? .* at %s:%s, .*> '
r'was never yielded from\n'
- r'Coroutine object created at \(most recent call last\):\n'
+ r'Coroutine object created at \(most recent call last, truncated to \d+ last lines\):\n'
r'.*\n'
r' File "%s", line %s, in test_coroutine_never_yielded\n'
r' coro_noop\(\)$'
--- /dev/null
+Reduce performance overhead of asyncio debug mode.