четверг, 1 апреля 2021 г. в 15:27:01 UTC+3, Chris Angelico:
> On Thu, Apr 1, 2021 at 10:56 PM Alexey <zen.su...@gmail.com> wrote:
> >
> > Found it. As I said before the problem was lurking in the cache.
> > Few days ago I read about circular references and things like that and
> > I thought to myself that it might be the case. To build the cache I was
> > using lots of 'setdefault' methods chained together
> >
> > self.__cache.setdefault(cluster_name, {}).setdefault(database_name, {})...
> >
> > and instead of wring a long lines I decided to divide it to increase
> > readability
> >
> > cluster = self.__cache.setdefault(cluster_name, {})
> > database = database.setdefault(database_name, {})
> > ...
> > and I guess that was the problem.
> >
> > First thing I did was to rewrite this back to single line.
> If the cache is always and only used in this way, it might be cleaner
> to use a defaultdict(dict) instead of the setdefault calls. Or, since
> this appears to be a two-level cache:
>
> self.__cache = defaultdict(lambda: defaultdict(dict))
>
> and then you can simply reference
> self.__cache[cluster_name][database_name] to read or update the cache.
I agree
> Having that be more efficient than either self.__cache=None or del
> self.__cache (which will be equivalent), I can understand. But better
> than clearing the dict? Seems very odd.
In this particular case 'cache.clear()' just don't work (in context of
releasing memory). If someone can tell me why, I'll be very thankful
> Ideally, though, you'd want to NOT have those reference loops. I
> presume the database objects need to have a reference to whatever
> 'self' is, but perhaps the cache can be done externally to the object,
> which would make all the references one-way instead of circular. But
> that's something only you can investigate.
I did some refactoring and changed my code already.
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