Python 2.x-Windows上毫秒级的睡眠调用 [英] Python 2.x - sleep call at millisecond level on Windows
问题描述
在这个论坛上,我得到了一些很好的关于如何用Python 2编写时钟对象的提示。我现在有一些代码在工作。时钟在60 FPS时滴答:
I was given some very good hints in this forum about how to code a clock object in Python 2. I've got some code working now. It's a clock that 'ticks' at 60 FPS:
import sys
import time
class Clock(object):
def __init__(self):
self.init_os()
self.fps = 60.0
self._tick = 1.0 / self.fps
print "TICK", self._tick
self.check_min_sleep()
self.t = self.timestamp()
def init_os(self):
if sys.platform == "win32":
self.timestamp = time.clock
self.wait = time.sleep
def timeit(self, f, args):
t1 = self.timestamp()
f(*args)
t2 = self.timestamp()
return t2 - t1
def check_min_sleep(self):
"""checks the min sleep time on the system"""
runs = 1000
times = [self.timeit(self.wait, (0.001, )) for n in xrange(runs)]
average = sum(times) / runs
print "average min sleep time:", round(average, 6)
sort = sorted(times)
print "fastest, slowest", sort[0], sort[-1]
def tick(self):
next_tick = self.t + self._tick
t = self.timestamp()
while t < next_tick:
t = self.timestamp()
self.t = t
if __name__ == "__main__":
clock = Clock()
时钟并没有太糟糕,但是为了避免繁忙的循环,我希望Windows的睡眠时间少于通常大约15毫秒。在我的系统(64位Windows 10)上,如果Python是唯一正在运行的应用程序,那么在启动时钟时,它平均会返回15/16毫秒。
The clock does not do too bad, but in order to avoid a busy loop I'd like Windows to sleep less than the usual about 15 milliseconds. On my system (64-bit Windows 10), it returns me an average of about 15 / 16 msecs when starting the clock if Python is the only application that's running. That's way too long for a min sleep to avoid a busy loop.
有人知道我怎样才能使Windows的睡眠时间少于这个值吗?
Does anybody know how I can get Windows to sleep less than that value?
推荐答案
您可以暂时将计时器期限降低到 timeGetDevCaps
。下面定义了一个 timer_resolution
上下文管理器,该上下文管理器调用 timeBeginPeriod
和 timeEndPeriod
函数。
You can temporarily lower the timer period to the wPeriodMin
value returned by timeGetDevCaps
. The following defines a timer_resolution
context manager that calls the timeBeginPeriod
and timeEndPeriod
functions.
import timeit
import contextlib
import ctypes
from ctypes import wintypes
winmm = ctypes.WinDLL('winmm')
class TIMECAPS(ctypes.Structure):
_fields_ = (('wPeriodMin', wintypes.UINT),
('wPeriodMax', wintypes.UINT))
def _check_time_err(err, func, args):
if err:
raise WindowsError('%s error %d' % (func.__name__, err))
return args
winmm.timeGetDevCaps.errcheck = _check_time_err
winmm.timeBeginPeriod.errcheck = _check_time_err
winmm.timeEndPeriod.errcheck = _check_time_err
@contextlib.contextmanager
def timer_resolution(msecs=0):
caps = TIMECAPS()
winmm.timeGetDevCaps(ctypes.byref(caps), ctypes.sizeof(caps))
msecs = min(max(msecs, caps.wPeriodMin), caps.wPeriodMax)
winmm.timeBeginPeriod(msecs)
yield
winmm.timeEndPeriod(msecs)
def min_sleep():
setup = 'import time'
stmt = 'time.sleep(0.001)'
return timeit.timeit(stmt, setup, number=1000)
示例
Example
>>> min_sleep()
15.6137827
>>> with timer_resolution(msecs=1): min_sleep()
...
1.2827173000000016
在 with
块之后恢复原始计时器分辨率:
The original timer resolution is restored after the with
block:
>>> min_sleep()
15.6229814
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