diff options
Diffstat (limited to 'Lib/threading.py')
| -rw-r--r-- | Lib/threading.py | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/Lib/threading.py b/Lib/threading.py index c5e65d9..74e93bb 100644 --- a/Lib/threading.py +++ b/Lib/threading.py @@ -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) |