perf(reactivity): avoid unnecessary recursion in removeSub

[skirtles-code]

I stumbled across an edge case where the performance of computed can go awry:

• Playground - 3.5.11

The time taken grows exponentially with the value of LAYERS. I used 22 in the example, but you may need to tweak it depending on your hardware.

The problem is with cleaning up the subs. removeSub() calls itself recursively if dep.subs is undefined. But in this example, deps.subs is always undefined for all deps, so it ends up calling removeSub() a huge number of times. The same links are being removed over and over.

I've attempted to fix it by additionally checking that deps.subs wasn't already undefined.

The diff makes the change look more complicated than it actually is. I've moved the if (dep.subs === link) { part further down and wrapped it around the clean-up section.

• Playground - this PR

[pkg-pr-new[bot]]

Open in Stackblitz

@vue/compiler-core

pnpm add https://pkg.pr.new/@vue/compiler-core@12135

@vue/compiler-sfc

pnpm add https://pkg.pr.new/@vue/compiler-sfc@12135

@vue/compiler-dom

pnpm add https://pkg.pr.new/@vue/compiler-dom@12135

@vue/compiler-ssr

pnpm add https://pkg.pr.new/@vue/compiler-ssr@12135

@vue/reactivity

pnpm add https://pkg.pr.new/@vue/reactivity@12135

@vue/runtime-core

pnpm add https://pkg.pr.new/@vue/runtime-core@12135

@vue/runtime-dom

pnpm add https://pkg.pr.new/@vue/runtime-dom@12135

@vue/shared

pnpm add https://pkg.pr.new/@vue/shared@12135

@vue/server-renderer

pnpm add https://pkg.pr.new/@vue/server-renderer@12135

vue

pnpm add https://pkg.pr.new/vue@12135

@vue/compat

pnpm add https://pkg.pr.new/@vue/compat@12135

commit: b225ac7

[github-actions[bot]]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	101 kB (-5 B)	38.1 kB (-1 B)	34.3 kB (+71 B)
vue.global.prod.js	160 kB (-5 B)	58 kB (-1 B)	51.5 kB (-32 B)

Usages

Name	Size	Gzip	Brotli
createApp (CAPI only)	49.1 kB (-5 B)	18.9 kB (-2 B)	17.3 kB (-1 B)
createApp	55.7 kB (-5 B)	21.4 kB (-2 B)	19.5 kB (-45 B)
createSSRApp	59.7 kB (-5 B)	23.1 kB (-1 B)	21.1 kB (+46 B)
defineCustomElement	60.4 kB (-5 B)	23 kB (-2 B)	20.9 kB (-9 B)
overall	69.4 kB (-5 B)	26.5 kB (-1 B)	24.1 kB (+42 B)

[edison1105]

/ecosystem-ci run

[vue-bot]

📝 Ran ecosystem CI: Open

suite	result	latest scheduled
language-tools	:x: failure	:x: failure
nuxt	:white_check_mark: success	:white_check_mark: success
pinia	:white_check_mark: success	:white_check_mark: success
primevue	:white_check_mark: success	:white_check_mark: success
quasar	:x: failure	:white_check_mark: success
radix-vue	:white_check_mark: success	:white_check_mark: success
router	:white_check_mark: success	:white_check_mark: success
test-utils	:white_check_mark: success	:white_check_mark: success
vant	:white_check_mark: success	:white_check_mark: success
vite-plugin-vue	:white_check_mark: success	:white_check_mark: success
vitepress	:white_check_mark: success	:white_check_mark: success
vue-i18n	:white_check_mark: success	:white_check_mark: success
vue-macros	:white_check_mark: success	:white_check_mark: success
vuetify	:white_check_mark: success	:white_check_mark: success
vueuse	:white_check_mark: success	:white_check_mark: success
vue-simple-compiler	:white_check_mark: success	:white_check_mark: success

[edison1105]

/ecosystem-ci run quasar

[vue-bot]

📝 Ran ecosystem CI: Open

suite	result	latest scheduled
quasar	:white_check_mark: success	:white_check_mark: success