8000 gh-122881: Reduce asyncio heapq scheduling overhead by bdraco · Pull Request #122882 · python/cpython · GitHub
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gh-122881: Reduce asyncio heapq scheduling overhead #122882

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564394e
Reduce asyncio heapq scheduling overhead
bdraco Aug 10, 2024
3b46d71
📜🤖 Added by blurb_it.
blurb-it[bot] Aug 10, 2024
f01857d
Update Lib/asyncio/base_events.py
bdraco Aug 10, 2024
a866d33
Update Misc/NEWS.d/next/Library/2024-08-10-13-10-45.gh-issue-122881.z…
bdraco Aug 10, 2024
0205d0b
Update Misc/NEWS.d/next/Library/2024-08-10-13-10-45.gh-issue-122881.z…
bdraco Aug 11, 2024
fdda416
tweaks from review comments
bdraco Aug 11, 2024
88a04d4
Merge remote-tracking branch 'bdraco/speed_up_async_schedule' into sp…
bdraco Aug 11, 2024
345c939
Merge branch 'main' into speed_up_async_schedule
bdraco Aug 11, 2024
4b9aed8
tweak from suggestion
bdraco Aug 12, 2024
6753682
Merge branch 'main' into speed_up_async_schedule
bdraco Aug 12, 2024
ca5cc25
TimerHandle scheduling can be quantified, _run_once imporvement will …
bdraco Aug 12, 2024
a5b6647
access self more often
bdraco Aug 12, 2024
5ccc55f
Merge branch 'main' into speed_up_async_schedule
bdraco Aug 24, 2024
f78838c
Update Lib/asyncio/base_events.py
bdraco Aug 24, 2024
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23 changes: 12 additions & 11 deletions Lib/asyncio/base_events.py
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Original file line number Diff line number Diff line change
Expand Up @@ -812,7 +812,10 @@ def call_at(self, when, callback, *args, context=None):
timer = events.TimerHandle(when, callback, args, self, context)
if timer._source_traceback:
del timer._source_traceback[-1]
heapq.heappush(self._scheduled, timer)
# The `TimerHandle` is wrapped in a tuple to avoid calling the
# `TimerHandle.__lt__` method since the `heapq` operations
# will need to compare against many other `TimerHandler` objects.
heapq.heappush(self._scheduled, (when, timer))
timer._scheduled = True
return timer

Expand Down Expand Up @@ -1959,28 +1962,29 @@ def _run_once(self):
# Remove delayed calls that were cancelled if their number
# is too high
new_scheduled = []
for handle in self._scheduled:
for when_handle in self._scheduled:
handle = when_handle[1]
if handle._cancelled:
handle._scheduled = False
else:
new_scheduled.append(handle)
new_scheduled.append(when_handle)

heapq.heapify(new_scheduled)
self._scheduled = new_scheduled
self._timer_cancelled_count = 0
else:
# Remove delayed calls that were cancelled from head of queue.
while self._scheduled and self._scheduled[0]._cancelled:
while self._scheduled and self._scheduled[0][1]._cancelled:
self._timer_cancelled_count -= 1
handle = heapq.heappop(self._scheduled)
_, handle = heapq.heappop(self._scheduled)
handle._scheduled = False

timeout = None
if self._ready or self._stopping:
timeout = 0
elif self._scheduled:
# Compute the desired timeout.
timeout = self._scheduled[0]._when - self.time()
timeout = self._scheduled[0][0] - self.time()
if timeout > MAXIMUM_SELECT_TIMEOUT:
timeout = MAXIMUM_SELECT_TIMEOUT
elif timeout < 0:
Expand All @@ -1993,11 +1997,8 @@ def _run_once(self):

# Handle 'later' callbacks that are ready.
end_time = self.time() + self._clock_resolution
while self._scheduled:
handle = self._scheduled[0]
if handle._when >= end_time:
break
handle = heapq.heappop(self._scheduled)
while self._scheduled and self._scheduled[0][0] < end_time:
_, handle = heapq.heappop(self._scheduled)
handle._scheduled = False
self._ready.append(handle)

Expand Down
12 changes: 6 additions & 6 deletions Lib/test/test_asyncio/test_base_events.py
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Original file line number Diff line number Diff line change
Expand Up @@ -268,7 +268,7 @@ def cb():

h = self.loop.call_later(10.0, cb)
self.assertIsInstance(h, asyncio.TimerHandle)
self.assertIn(h, self.loop._scheduled)
self.assertIn((h.when(), h), self.loop._scheduled)
self.assertNotIn(h, self.loop._ready)
with self.assertRaises(TypeError, msg="delay must not be None"):
self.loop.call_later(None, cb)
Expand Down Expand Up @@ -378,13 +378,13 @@ def test__run_once(self):
h1.cancel()

self.loop._process_events = mock.Mock()
self.loop._scheduled.append(h1)
self.loop._scheduled.append(h2)
self.loop._scheduled.append((h1.when(), h1))
self.loop._scheduled.append((h2.when(), h2))
self.loop._run_once()

t = self.loop._selector.select.call_args[0][0]
self.assertTrue(9.5 < t < 10.5, t)
self.assertEqual([h2], self.loop._scheduled)
self.assertEqual([(h2.when(), h2)], self.loop._scheduled)
self.assertTrue(self.loop._process_events.called)

def test_set_debug(self):
Expand All @@ -406,7 +406,7 @@ def cb(loop):
self.loop, None)

self.loop._process_events = mock.Mock()
self.loop._scheduled.append(h)
self.loop._scheduled.append((h.when(), h))
self.loop._run_once()

self.assertTrue(processed)
Expand Down Expand Up @@ -486,7 +486,7 @@ def cb():
self.assertEqual(len(self.loop._scheduled), not_cancelled_count)

# Ensure only uncancelled events remain scheduled
self.assertTrue(all([not x._cancelled for x in self.loop._scheduled]))
self.assertTrue(all([not x._cancelled for _, x in self.loop._scheduled]))

def test_run_until_complete_type_error(self):
self.assertRaises(TypeError,
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2024-08-10-13-10-45.gh-issue-122881.z_n6W-.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Reduced :mod:`asyncio` :mod:`heapq` scheduling overhead. Scheduling and running an :class:`asyncio.TimerHandle` is now roughly 9.5% faster.
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