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_Condition.wait(): never sleep longer than the timeout time remaining, 

and even if we have a long time left to wait, try the lock at least 20
times/second.
This commit is contained in:
Tim Peters 2001-08-12 00:41:33 +00:00
parent ce3016a142
commit a6a4f27ef7
1 changed files with 11 additions and 4 deletions
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15
Lib/threading.py
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@ -191,15 +191,22 @@ class _Condition(_Verbose):
if __debug__:
self._note("%s.wait(): got it", self)
else:
# Balancing act: We can't afford a pure busy loop, so we
# have to sleep; but if we sleep the whole timeout time,
# we'll be unresponsive. The scheme here sleeps very
# little at first, longer as time goes on, but never longer
# than 20 times per second (or the timeout time remaining).
endtime = _time() + timeout
delay = 0.000001 # 1 usec
delay = 0.0005 # 500 us -> initial delay of 1 ms
while 1:
gotit = waiter.acquire(0)
if gotit or _time() >= endtime:
if gotit:
break
remaining = endtime - _time()
if remaining <= 0:
break
delay = min(delay * 2, remaining, .05)
_sleep(delay)
if delay < 1.0:
delay = delay * 2.0
if not gotit:
if __debug__:
self._note("%s.wait(%s): timed out", self, timeout)