GH-116090: Fix test and clarify behavior for exception events when exhausting a generator. (GH-120697)

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Mark Shannon 2024-07-26 14:37:35 +01:00 committed by GitHub
parent 95a73917cd
commit 2c42e13e80
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2 changed files with 33 additions and 6 deletions

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@ -226,6 +226,10 @@ To allow tools to monitor for real exceptions without slowing down generators
and coroutines, the :monitoring-event:`STOP_ITERATION` event is provided.
:monitoring-event:`STOP_ITERATION` can be locally disabled, unlike :monitoring-event:`RAISE`.
Note that the :monitoring-event:`STOP_ITERATION` event and the :monitoring-event:`RAISE`
event for a :exc:`StopIteration` exception are equivalent, and are treated as interchangeable
when generating events. Implementations will favor :monitoring-event:`STOP_ITERATION` for
performance reasons, but may generate a :monitoring-event:`RAISE` event with a :exc:`StopIteration`.
Turning events on and off
-------------------------

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@ -832,20 +832,43 @@ class ExceptionMonitoringTest(CheckEvents):
self.check_events(func1, [("raise", KeyError)])
# gh-116090: This test doesn't really require specialization, but running
# it without specialization exposes a monitoring bug.
@requires_specialization
def test_implicit_stop_iteration(self):
"""Generators are documented as raising a StopIteration
when they terminate.
However, we don't do that if we can avoid it, for speed.
sys.monitoring handles that by injecting a STOP_ITERATION
event when we would otherwise have skip the RAISE event.
This test checks that both paths record an equivalent event.
"""
def gen():
yield 1
return 2
def implicit_stop_iteration():
for _ in gen():
def implicit_stop_iteration(iterator=None):
if iterator is None:
iterator = gen()
for _ in iterator:
pass
self.check_events(implicit_stop_iteration, [("raise", StopIteration)], recorders=(StopiterationRecorder,))
recorders=(ExceptionRecorder, StopiterationRecorder,)
expected = [("raise", StopIteration)]
# Make sure that the loop is unspecialized, and that it will not
# re-specialize immediately, so that we can we can test the
# unspecialized version of the loop first.
# Note: this assumes that we don't specialize loops over sets.
implicit_stop_iteration(set(range(100)))
# This will record a RAISE event for the StopIteration.
self.check_events(implicit_stop_iteration, expected, recorders=recorders)
# Now specialize, so that we see a STOP_ITERATION event.
for _ in range(100):
implicit_stop_iteration()
# This will record a STOP_ITERATION event for the StopIteration.
self.check_events(implicit_stop_iteration, expected, recorders=recorders)
initial = [
("raise", ZeroDivisionError),