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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Re-entering pairwise.__next__() leaks references","articleBody":"Re-entering the `__next__()` method of itertools.pairwise leaks references, because *old* hold a borrowed reference when the `__next__()` method of the underlying iterator is called. It may potentially lead to the use of a freed memory and a crash, but I only have reproducer for leaks.\r\n\r\nEven if the re-entrant call is not very meaningful, it should correctly count references. There are several ways to fix this issue. I choose the simplest one which matches the current results (only without leaks) in most of simple tests, even if there is no other reasons to prefer these results.\r\n\r\ncc @rhettinger\r\n\n\n\u003c!-- gh-linked-prs --\u003e\n### Linked PRs\n* gh-109788\n* gh-112699\n* gh-112700\n\u003c!-- /gh-linked-prs --\u003e\n","author":{"url":"https://github.com/serhiy-storchaka","@type":"Person","name":"serhiy-storchaka"},"datePublished":"2023-09-23T11:39:23.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/109786/cpython/issues/109786"}