#28342: Make PyLibMCCache backend catch exceptions when memcached server is down
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Reporter: Julian Andrews | Owner: Julian
Type: | Andrews
Cleanup/optimization | Status: assigned
Component: Core (Cache system) | Version: 1.11
Severity: Normal | Resolution:
Keywords: memcached cache | Triage Stage: Accepted
pylibmc |
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Comment (by Julian Andrews):
I've written up a patch here: https://github.com/django/django/pull/8681.
I looked at the `django-pylibmc` code, and it was very similar to what I
was already doing, but there are a few differences.
First, `django-pylibmc` seems to be returning `False` to indicate failure
for a bunch of methods (and `None` to indicate success). Given that that
differs from the `MemcachedCache` behavior, and that the `False` vs.
`None` distinction is sort of confusing, I decided to stick with the
default behavior. I actually like the idea of a return value that
indicates if cache fetch was successful, but in that case, the relevant
methods should probably always return `True` or `False`, and that behavior
should be consistent across backends. I decided not to do that as part of
this PR.
Second, `django-pylibmc` includes logging of errors. I actually *really*
like that, but again, it's not consistent with the other backend behavior,
so I didn't include that. I could add logging though I'm not really that
familiar with the django logging conventions, so some pointers on that
would be helpful!
Third, `django-pylibmc` was never catching `ConnectionError`s. As far as I
can tell, when the memcached server goes down, the first error gets a
`ConnectionError` and then later ones throw `ServerDown` so I'm pretty
sure we need to catch both.
--
Ticket URL: <https://code.djangoproject.com/ticket/28342#comment:4>
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