"Notification ranker" - what does it do, and what happens if I disable it?

Question

After staying for so long on Marshmallow, today I finally made the decision to upgrade one of my secondary devices with Nougat (LineageOS 14.1 to be precise). Everything went smooth and most things stayed familiar... except this weird entry in Settings - Developer options - Running services.

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I'd keep the running process list as clean as possible (habit, don't question why), but when I clicked into this "Android Services Library" and tried to stop it, it says it runs a "Notification ranker service" (second screenshot).

Clicking "Settings" there takes me to an app preference screen (third screenshot; likely the same as in Settings - Apps) that contains nothing about the service or the app:

Furthermore, I can't find any reference on how this "notification ranker" mechanism works, or even what it is.

Note that I also flashed stock Nougat on my Nexus 6P before, and from what I remember, that one also has this service running, so it's not specific to LineageOS.

Can anyone with sufficient knowledge tell me what it does, and what will happen if I disable this service via external means, e.g. will notification functions be affected?

Answer 1

From arstechnica:

GoogleExtServices has an app name of "Android Services Library" and does actually contain something: an "Android Notification Ranking Service." A "Notification Ranking Service" was added in Lollipop, and it sorts notifications by "importance" based on things like freshness, app type (IM apps come first), and by contact. This seems to be an extension to the system that includes support for Nougat's "notification bundling" feature. This is a really minor feature, and with only this single chunk of code, GoogleExtServices weighs in at a microscopic 10KB.

Answer 2

Now for the last part of the question...

...will notification functions be affected?

I just jumped ship to Nougat with my primary device (Nexus 6P), and disabled the service right away, and while I set other things up, all notifications continue to pour in normally, so it definitely does not affect the basics. It will probably affect the fine-grained notification priority in Settings, but since I only use the 2 extremes ("fully on" or "fully off"), this isn't of concern.

Answer 3

I am not sure about lineage OS, but I hope it will be similar to (Show notification - block all - Don't silence or block) which is default in Nougat. My Oneplus 3 has something similar to this and it has 5 levels. Maybe Notification Controls will something like this.