[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Dong-hee Na]

Change by Dong-hee Na :


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stage: patch review -> resolved
status: open -> closed

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Łukasz Langa]

Łukasz Langa  added the comment:


New changeset fc4474e45eecbea8e88095f28c98c5d56438d841 by Dong-hee Na in branch 
'main':
bpo-45429: Merge whatsnew about time.sleep (GH-29589)
https://github.com/python/cpython/commit/fc4474e45eecbea8e88095f28c98c5d56438d841


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nosy: +lukasz.langa

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Dong-hee Na]

Change by Dong-hee Na :


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pull_requests: +27832
pull_request: https://github.com/python/cpython/pull/29589

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Dong-hee Na]

Dong-hee Na  added the comment:


New changeset 55868f1a335cd3853938082a5b25cfba66563135 by Dong-hee Na in branch 
'main':
bpo-45429: Support CREATE_WAITABLE_TIMER_HIGH_RESOLUTION if possible (GH-29203)
https://github.com/python/cpython/commit/55868f1a335cd3853938082a5b25cfba66563135


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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Dong-hee Na]

Dong-hee Na  added the comment:

AS-IS:
average:  0.015609736680984497

TO-BE:
average:  2.7387380599975585e-05

Impressive result :)

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Added file: https://bugs.python.org/file50392/bpo-45429.py

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Dong-hee Na]

Change by Dong-hee Na :


--
keywords: +patch
pull_requests: +27472
stage:  -> patch review
pull_request: https://github.com/python/cpython/pull/29203

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Benjamin Szőke]

Benjamin Szőke  added the comment:

A similar solution was introduced in VirtualBox some months ago. Soon, i could 
get back my Windows 10 developing PC and i can try this things.

https://www.virtualbox.org/browser/vbox/trunk/src/VBox/Runtime/r3/win/timer-win.cpp#L312

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Benjamin Szőke]

Change by Benjamin Szőke :


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nosy: +Livius

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Eryk Sun]

Eryk Sun  added the comment:

It's up to the core devs whether or not Python should try to use a 
high-resolution timer, which is currently undocumented in the Windows API and 
implemented only in recent releases of Windows 10 and 11. But if this does get 
supported, the code should fall back on creating a normal timer if 
CREATE_WAITABLE_TIMER_HIGH_RESOLUTION makes the call fail. For example:

#ifndef CREATE_WAITABLE_TIMER_HIGH_RESOLUTION
#define CREATE_WAITABLE_TIMER_HIGH_RESOLUTION 0x0002
#endif

LARGE_INTEGER relative_timeout;
// No need to check for integer overflow, both types are signed
assert(sizeof(relative_timeout) == sizeof(timeout_100ns));
// SetWaitableTimerEx(): a negative due time is relative
relative_timeout.QuadPart = -timeout_100ns;
DWORD flags = CREATE_WAITABLE_TIMER_HIGH_RESOLUTION;

create_timer:

HANDLE timer = CreateWaitableTimerExW(NULL, NULL, flags, 
TIMER_ALL_ACCESS);
if (timer == NULL)
{
if (flags && GetLastError() == ERROR_INVALID_PARAMETER) {
// CREATE_WAITABLE_TIMER_HIGH_RESOLUTION is not supported.
flags = 0;
goto create_timer;
}
PyErr_SetFromWindowsErr(0);
return -1;
}

if (!SetWaitableTimerEx(timer, _timeout,
  0,  // no period; the timer is signaled once
  NULL, NULL, // no completion routine
  NULL,   // no wake context; do not resume from suspend
  0)) // no tolerable delay for timer coalescing
{
PyErr_SetFromWindowsErr(0);
goto error;
}

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nosy: +eryksun

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[STINNER Victor]

STINNER Victor  added the comment:

See also bpo-19007: "precise time.time() under Windows 8: use 
GetSystemTimePreciseAsFileTime".

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[Dong-hee Na]

Change by Dong-hee Na :


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nosy: +corona10

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[STINNER Victor]

STINNER Victor  added the comment:

The Go programming language called timeBeginPeriod(1) to get more accurate 
timers. With the following change, it can now use a high resolution timer 
(CREATE_WAITABLE_TIMER_HIGH_RESOLUTION) to sleep:
https://go-review.googlesource.com/c/go/+/248699/

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[STINNER Victor]

STINNER Victor  added the comment:

See also: https://groups.google.com/a/chromium.org/g/scheduler-dev/c/0GlSPYreJeY

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[STINNER Victor]

Change by STINNER Victor :


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components: +Windows
nosy: +paul.moore, steve.dower, tim.golden, zach.ware

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[issue45429] [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION

[STINNER Victor]

New submission from STINNER Victor :

In bpo-21302, the Windows implementation of time.sleep() was modified to use a 
waitable timer:

New changeset 58f8adfda3c2b42f654a55500e8e3a6433cb95f2 by Victor Stinner in 
branch 'main':
bpo-21302: time.sleep() uses waitable timer on Windows (GH-28483)
https://github.com/python/cpython/commit/58f8adfda3c2b42f654a55500e8e3a6433cb95f2

It now calls the functions:

* CreateWaitableTimerW()
* SetWaitableTimer()
* WaitForMultipleObjects()

While SetWaitableTimer() has a resolution of 100 ns, the timer has a resolution 
of 15.6 ms in practice.

We could use the undocumented CREATE_WAITABLE_TIMER_HIGH_RESOLUTION flag with 
CreateWaitableTimerEx(). See: https://bugs.python.org/issue21302#msg403550

See also:

* 
https://randomascii.wordpress.com/2013/07/08/windows-timer-resolution-megawatts-wasted/
* https://vstinner.readthedocs.io/windows.html#time

--
components: Library (Lib)
messages: 403631
nosy: vstinner
priority: normal
severity: normal
status: open
title: [Windows] time.sleep() should use CREATE_WAITABLE_TIMER_HIGH_RESOLUTION
type: enhancement
versions: Python 3.11

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