Your use case is valid, there are times in which I'd like a strong reference to be kept. But there are also lots of times I want it to not be kept. Then I would offer this feature as a flag `weakref=True` with a default of `False`. What do you think?
On Thu, Oct 15, 2020 at 9:10 PM <ed...@211mainstreet.net> wrote: > Usually when I use lru_cache I don't want items to randomly disappearing > from the cache. Just because a key isn't referenced anywhere else doesn't > mean that I want it to automatically disappear. That is the whole point. > Take this example: > > @lru_cache > def expensive_function(a,b,c): > return a**b**c > > #no reference kept, so the weakref key gets evicted. > print(expensive_function(5000,5000,5000)) > #calls expensive_function all over again > print(expensive_function(5000,5000,5000)) > > Doesn't your idea take away half the point of lru_cache, or am I not > understanding your suggestion? > > > October 15, 2020 1:49 PM, "Ram Rachum" <r...@rachum.com > <r...@rachum.com?to=%22ram%20rachum%22%20%3c...@rachum.com%3E>> wrote: > > Hi everyone, > For many years, I've used a `cache` decorator that I built > <https://github.com/cool-RR/python_toolbox/blob/master/python_toolbox/caching/decorators.py#L36> > for caching Python functions. Then `functools.lru_cache` was implemented, > which is much more standard. However, as far as I know, it holds normal > references to its keys, rather than weak references. This means that it can > cause memory leaks when it's storing items that don't have any references > elsewhere. This often makes me reluctant to use it. > What do you think about supporting weakrefs in for keys lru_cache? > If I remember correctly, the main difficulty was that not all keys are of > a type that can be weakreffed. If I remember correctly again, I've solved > this by including logic that attempts a weakref when possible, and degrades > to a strong ref. What do you think about that? > Thanks, > Ram. > > > >
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