facebookexperimental/Recoil

[Performance] Short-circuit set recoil state if the value is unchanged

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#1927 opened on Jul 30, 2022

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 (7 comments) (1 reaction) (0 assignees)JavaScript (19,428 stars) (1,151 forks)batch import
help wantedperformance

Description

It seems that the current implementation of setting recoil state can be further improved when the value is the same as the current value. In this case, we don't have to go through all the enchilada and more importantly don't have to call setState in the end, which is not exactly cost free. I have observed major performance hit thanks to that. I have to cache the previous value myself and do the equality check before calling set recoil state when recoil has all the knowledge to that.

Contributor guide

Tech stack
javascriptreact
Domain
performancefrontend
Issue type
performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
JavaScriptReactRecoil fundamentals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
40
Research direction
Look at the Recoil source code related to state updates, specifically the `setRecoilState` function. Identify where the state is updated and add an equality check to short circuit if the value is unchanged. Consider using a shallow comparison for objects. Check existing comments for additional context.