bpo-30306: release arguments of contextmanager (GH-1500)
The arguments to a generator function which is declared as a
contextmanager are stored inside the context manager, and
thus are kept alive, even when it is used as a regular context
manager, and not as a function decorator (where it needs
the original arguments to recreate the generator on each
call).
This is a possible unnecessary memory leak, so this changes
contextmanager.__enter__ to release the saved arguments,
as that method being called means that particular CM instance
isn't going to need to recreate the underlying generator.
Patch by Martin Teichmann.
diff --git a/Lib/contextlib.py b/Lib/contextlib.py
index ef8f8c9..1ff8cdf 100644
--- a/Lib/contextlib.py
+++ b/Lib/contextlib.py
@@ -105,6 +105,9 @@
return self.__class__(self.func, self.args, self.kwds)
def __enter__(self):
+ # do not keep args and kwds alive unnecessarily
+ # they are only needed for recreation, which is not possible anymore
+ del self.args, self.kwds, self.func
try:
return next(self.gen)
except StopIteration: