bpo-39198: Ensure logging global lock is released on exception in isEnabledFor (GH-17689) (GH-17898)

(cherry picked from commit 950c679)

Author: miss-islington

Lib/logging/__init__.py

@@ -1619,12 +1619,15 @@ def isEnabledFor(self, level):
  return self._cache[level]
  except KeyError:
  _acquireLock()
- if self.manager.disable >= level:
- is_enabled = self._cache[level] = False
- else:
- is_enabled = self._cache[level] = level >= self.getEffectiveLevel()
- _releaseLock()
-
+ try:
+ if self.manager.disable >= level:
+ is_enabled = self._cache[level] = False
+ else:
+ is_enabled = self._cache[level] = (
+ level >= self.getEffectiveLevel()
+ )
+ finally:
+ _releaseLock()
  return is_enabled
 
  def getChild(self, suffix):

Misc/NEWS.d/next/Library/2020-01-02-20-21-03.bpo-39198.nzwGyG.rst

@@ -0,0 +1 @@
+If an exception were to be thrown in `Logger.isEnabledFor` (say, by asyncio timeouts or stopit) , the `logging` global lock may not be released appropriately, resulting in deadlock. This change wraps that block of code with `try...finally` to ensure the lock is released.