Re: [Python-Dev] Why not using "except: (...) raise" to cleanup on error?
It is currently a general convention in asyncio to only catch Exception, not BaseException. I consider this a flaw and we should fix it, but it's unfortunately not so easy -- the tests will fail if you replace all occurrences of Exception with BaseException, and it is not always clear what's the right thing to do. E.g. catching KeyboardInterrupt may actually make it harder to stop a runaway asyncio app.
We should move this discussion to the issue tracker.
On Mon, Jun 4, 2018 at 9:11 AM, Victor Stinner vstinner@redhat.com wrote:
Hi,
I just read a recent bugfix in asyncio:
https://github.com/python/cpython/commit/9602643120a509858d0bee4215d7f1 50e6125468
- try:
- await waiter
- except Exception:
- transport.close()
- raise
Why only catching "except Exception:"? Why not also catching KeyboardInterrupt or MemoryError? Is it a special rule for asyncio, or a general policy in Python stdlib?
For me, it's fine to catch any exception using "except:" if the block contains "raise", typical pattern to cleanup a resource in case of error. Otherwise, there is a risk of leaking open file or not flushing data on disk, for example.
Victor
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