Memory Leak in RelationController with bigger datasets

[viamage]

Expected behavior

RelationController supports big related datasets of related models without memory leaks.

Actual behavior

On example of HasMany relation, with around 100k related records php eats huge amounts of RAM when trying to access controller.

Reproduce steps

Seed any HasMany relation with a big dataset, setup relation controller for parent and try to access parent model in backend.

To make things easier I prepared simple plugin - https://github.com/viamage/relationsbug

It will create Category and Products models, will seed Products with 100 000 records and provide basic controller. Product is quite simple model with some name,slug, some text in description and metadata.

Debugging with:

October/Rain/Database/Relations/HasMany, line 78:

    public function getSimpleValue()
    {
        ini_set('memory_limit', '2048M');
        $value = null;
        $relationName = $this->relationName;

        if ($relation = $this->parent->$relationName) {
            $value = $relation->pluck($this->localKey)->all();
        }
        dd(memory_get_peak_usage() / 1024 / 1024);
        return $value;
    }

PHP takes 1300 MB memory to load this, thus will crash on most environments.

October build

443

Possible solution

If I change line 84 to call QueryBuilder instead of making collection to pluck later:

    public function getSimpleValue()
    {
        $value = null;
        $relationName = $this->relationName;

        if ($relation = $this->parent->$relationName()) {
            $value = $relation->pluck($this->localKey)->all();
        }

        return $value;
    }

RAM usage drops from 1300MB to 64 MB and all works as expected (is obviously as slow as it was without (), because of ->count() methods, but we can't avoid that I guess).

I am not sure if it makes sense to create Collection here if we need it only to pluck and thus create array immediately after? Are you open to accept PR that would resolve this?

Or is there some other way to solve this without touching Rain library?

[LukeTowers]

@viamage I would accept a PR to fix this