Issue #7316: the acquire() method of lock objects in the :mod:`threading`
module now takes an optional timeout argument in seconds. Timeout support
relies on the system threading library, so as to avoid a semi-busy wait
loop.
diff --git a/Lib/threading.py b/Lib/threading.py
index 9f1525d..b4d07fe 100644
--- a/Lib/threading.py
+++ b/Lib/threading.py
@@ -31,6 +31,7 @@
_CRLock = _thread.RLock
except AttributeError:
_CRLock = None
+TIMEOUT_MAX = _thread.TIMEOUT_MAX
del _thread
@@ -107,14 +108,14 @@
return "<%s owner=%r count=%d>" % (
self.__class__.__name__, owner, self._count)
- def acquire(self, blocking=True):
+ def acquire(self, blocking=True, timeout=-1):
me = _get_ident()
if self._owner == me:
self._count = self._count + 1
if __debug__:
self._note("%s.acquire(%s): recursive success", self, blocking)
return 1
- rc = self._block.acquire(blocking)
+ rc = self._block.acquire(blocking, timeout)
if rc:
self._owner = me
self._count = 1
@@ -234,22 +235,10 @@
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 = 0.0005 # 500 us -> initial delay of 1 ms
- while True:
- gotit = waiter.acquire(0)
- if gotit:
- break
- remaining = endtime - _time()
- if remaining <= 0:
- break
- delay = min(delay * 2, remaining, .05)
- _sleep(delay)
+ if timeout > 0:
+ gotit = waiter.acquire(True, timeout)
+ else:
+ gotit = waiter.acquire(False)
if not gotit:
if __debug__:
self._note("%s.wait(%s): timed out", self, timeout)