Discussion: Remove the cache from users' hands/concerns?

[cakedev0]

Product vision: users should not interact with caching, they should only know it's there and enjoy the benefits.

Hence, I suggest to:

• remove clear_cache: this should be our responsibility to clear the cache when needed / make it light in memory.
• remove cache_predictions and instead compute predictions once for all at init time. You have no reason to build a report if you're not interested in prediction. And if we make reports immutable as I suggest here: Discussion: Make reports more immutable - remove setters for X_test, y_test, pos_label? #2553, you can do that in a much easier way.

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Note that currently cache_predictions store many redundant information in cache for classification, even duplicates (and quite a lot of duplicates for multiclass classification). Indeed, _get_cached_response_values is called for each possible pos_label while the returned values for predict_proba or decision_function are the same in the case of multiclass classification... I can write a quick fix for that, but I'd prefer writing a clean refactor instead. Also predict result can be deduced from predict_proba/decision_function, this is an optimization we don't do but that could be valuable for some models like KNeighbors[...].

=> I feel that instead of helping users to speed things up, we're slowing them down... I could craft an example where cache_predictions takes 10 minutes while it should rather have taken 20s...

[auguste-probabl]

I agree about removing cache_predictions; but as a user I would rather have the choice to clear the cache if I want to (although I guess I have the escape hatch of report._cache={}).

I am definitely in favor of reworking the cache to make it more efficient.

[cakedev0]

but as a user I would rather have the choice to clear the cache if I want to

For me having this method trigger a red light in my head "ah maybe the cache can grow huge and cause OOM, I need to clear it whenever I can". This is a burden I'd rather not have. But if it's indeed the case, then yes I need clear_cache.

Though for now, I think we can manage with a very light cache that users don't need to care about.

[cakedev0]

reworking the cache

Well here what I propose it not really to rework it, but to remove it for the predictions ("compute predictions once for all at init time"), and maybe store predictions as attributes (which could maybe become @cached_property later, if we really see the need for caching lazy computation).