René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Clients do not clean up Requests sessions","articleBody":"#### Environment details\r\n\r\n  - OS type and version: macOS\r\n  - Python version: 3.9\r\n  - `google-cloud-core` version: 1.4.3\r\n  - `google-cloud-storage` version: 1.33.0 (since it's related)\r\n\r\n#### Steps to reproduce\r\n\r\nThis is a sibling issue to https://github.com/googleapis/google-auth-library-python/issues/658 and as such the below is similar to that issue.\r\n\r\n[Py.test 6.2 enables hard errors on unhandled thread exceptions and resource errors](https://docs.pytest.org/en/stable/usage.html#warning-about-unraisable-exceptions-and-unhandled-thread-exceptions) such as leaking sockets/SSL sockets/FDs/.... I've spent the last couple hours debugging various\r\n\r\n```\r\nResourceWarning: unclosed \u003cssl.SSLSocket fd=12, family=AddressFamily.AF_INET, type=SocketKind.SOCK_STREAM, proto=0, laddr=('192.168.1.23', 60522), raddr=('216.58.207.202', 443)\u003e\r\n```\r\n\r\nWhen initiating (e.g.) a [`google-cloud-storage` storage client](https://github.com/googleapis/python-storage) with e.g.\r\n\r\n```python\r\n        creds = self.get_client_credentials()\r\n        return storage.Client(project=creds.project_id, credentials=creds)\r\n```\r\n\r\nthe client object is initialized with no explicit `_http` object, and the [default code path](https://github.com/googleapis/python-cloud-core/blob/d01c825d4b7638e76d9d2883baba5a91c884e310/google/cloud/client.py#L172-L184) is run, creating a new `requests.Session()` that will be _eventually_ GC'd but is otherwise not [`close()`d](https://requests.readthedocs.io/en/latest/api/#requests.Session.close), leading to the above warning (and a dropped connection and socket, which may have implications down the line).\r\n\r\nSince `google.core.client.Client` doesn't implement e.g. the context manager protocol or `close()`, there's no officially sanctioned way to clean up that session; for a storage Client, I subclassed one as a workaround but it would be nice if Clients had an official `close()`.\r\n\r\n```python\r\n        class CloseableStorageClient(storage.Client):\r\n            def __enter__(self):\r\n                return self\r\n\r\n            def __exit__(self, *args):\r\n                self._http.close()\r\n```\r\n\r\n#### Resolution suggestion\r\n\r\nAt the very least, add `close()` to `Client`s; by default it should probably only be something like\r\n  ```python\r\n  def close(self):\r\n      if self._http_internal:\r\n          self._http_internal.close()\r\n  ```\r\n, the semantics being a best-effort cleanup of resources allocated by the client, but not irreversible finalization.\r\n\r\nWith this, `Client`s could be used with [`contextlib.closing()`](https://docs.python.org/3.9/library/contextlib.html#contextlib.closing). Additionally, one could add a minimal context management protocol implementation á la\r\n\r\n```python\r\n            def __enter__(self):\r\n                return self\r\n\r\n            def __exit__(self, *args):\r\n                self.close()\r\n```\r\n\r\nIf you folks think this is a good way to go, I can certainly write the PR :)\r\n\r\ncc @busunkim96 (for having triaged the other issue).","author":{"url":"https://github.com/akx","@type":"Person","name":"akx"},"datePublished":"2020-12-22T19:02:03.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":4},"url":"https://github.com/64/python-cloud-core/issues/64"}