589f090d0b
This PR fixes two memory leaks I found debugging with @sokra. ## 1) Leak in `next-server.ts` The first leak was caused by the fact that the `require.cache` associated to the `next-server` module was not being cleared up properly, so we leaked context from modules required in that page, like API routes. ## 2) Leak with React Fetch When evaluating a route, we also evaluated the `react.shared-subset.development.js` module where React patches the `fetch` function. The problem is that when re-evaluating a route as part of hot reloading, we were patching over the previously patched `fetch` function. The result of this operation meant that we were keeping a reference to the context of the previous `fetch` and thus to the previous route context, thus creating a memory leak, since we only needed the new context. ## Test plan Checked manually the heap snapshots of a test app. ## Bug - [ ] Related issues linked using `fixes #number` - [ ] Integration tests added - [ ] Errors have a helpful link attached, see [`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md) ## Feature - [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR. - [ ] Related issues linked using `fixes #number` - [ ] [e2e](https://github.com/vercel/next.js/blob/canary/contributing/core/testing.md#writing-tests-for-nextjs) tests added - [ ] Documentation added - [ ] Telemetry added. In case of a feature if it's used or not. - [ ] Errors have a helpful link attached, see [`contributing.md`](https://github.com/vercel/next.js/blob/canary/contributing.md) ## Documentation / Examples - [ ] Make sure the linting passes by running `pnpm build && pnpm lint` - [ ] The "examples guidelines" are followed from [our contributing doc](https://github.com/vercel/next.js/blob/canary/contributing/examples/adding-examples.md)
110 lines
3.4 KiB
TypeScript
110 lines
3.4 KiB
TypeScript
import type { webpack } from 'next/dist/compiled/webpack/webpack'
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import { clearModuleContext } from '../../../server/web/sandbox'
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import { realpathSync } from 'fs'
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import path from 'path'
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import isError from '../../../lib/is-error'
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type Compiler = webpack.Compiler
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type WebpackPluginInstance = webpack.WebpackPluginInstance
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const originModules = [
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require.resolve('../../../server/require'),
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require.resolve('../../../server/load-components'),
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require.resolve('../../../server/next-server'),
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require.resolve('../../../compiled/react-server-dom-webpack/client'),
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]
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const RUNTIME_NAMES = ['webpack-runtime', 'webpack-api-runtime']
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function deleteCache(filePath: string) {
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try {
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filePath = realpathSync(filePath)
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} catch (e) {
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if (isError(e) && e.code !== 'ENOENT') throw e
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}
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const mod = require.cache[filePath]
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if (mod) {
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// remove the child reference from the originModules
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for (const originModule of originModules) {
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const parent = require.cache[originModule]
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if (parent) {
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const idx = parent.children.indexOf(mod)
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if (idx >= 0) parent.children.splice(idx, 1)
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}
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}
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// remove parent references from external modules
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for (const child of mod.children) {
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child.parent = null
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}
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delete require.cache[filePath]
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return true
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}
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return false
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}
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const PLUGIN_NAME = 'NextJsRequireCacheHotReloader'
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// This plugin flushes require.cache after emitting the files. Providing 'hot reloading' of server files.
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export class NextJsRequireCacheHotReloader implements WebpackPluginInstance {
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prevAssets: any = null
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hasServerComponents: boolean
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constructor(opts: { hasServerComponents: boolean }) {
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this.hasServerComponents = opts.hasServerComponents
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}
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apply(compiler: Compiler) {
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compiler.hooks.assetEmitted.tap(
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PLUGIN_NAME,
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(_file, { targetPath, content }) => {
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deleteCache(targetPath)
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clearModuleContext(targetPath, content.toString('utf-8'))
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}
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)
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compiler.hooks.afterEmit.tap(PLUGIN_NAME, (compilation) => {
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RUNTIME_NAMES.forEach((name) => {
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const runtimeChunkPath = path.join(
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compilation.outputOptions.path!,
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`${name}.js`
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)
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deleteCache(runtimeChunkPath)
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})
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let hasAppPath = false
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// we need to make sure to clear all server entries from cache
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// since they can have a stale webpack-runtime cache
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// which needs to always be in-sync
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const entries = [...compilation.entries.keys()].filter((entry) => {
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const isAppPath = entry.toString().startsWith('app/')
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hasAppPath = hasAppPath || isAppPath
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return entry.toString().startsWith('pages/') || isAppPath
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})
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if (hasAppPath) {
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// ensure we reset the cache for sc_server components
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// loaded via react-server-dom-webpack
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const reactServerDomModId = require.resolve(
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'next/dist/compiled/react-server-dom-webpack/client'
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)
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const reactServerDomMod = require.cache[reactServerDomModId]
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if (reactServerDomMod) {
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for (const child of reactServerDomMod.children) {
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child.parent = null
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delete require.cache[child.id]
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}
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}
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delete require.cache[reactServerDomModId]
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}
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entries.forEach((page) => {
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const outputPath = path.join(
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compilation.outputOptions.path!,
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page + '.js'
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)
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deleteCache(outputPath)
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})
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})
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}
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}
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