fix: EventEmitter memory leak when serving static pages from Node.js middleware by fa-sharp · Pull Request #15735 · withastro/astro

fa-sharp · 2026-03-03T09:51:20Z

Fixes #15730

Changes

This fixes an issue in the Node.js middleware handler that was causing an EventEmitter leak warning when serving static pages and files. For the requests that were being passed on to Express / Fastify (e.g. static files / pre-rendered pages / etc.), the socket listener and AbortController cleanup wasn't being run before calling next(). This fix makes sure to run the cleanup function before calling next() (I did need to add the cleanup function to the exports from 'astro/app/node', which doesn't feel ideal).
Ideally, these socket listeners shouldn't be created in the first place if the request is just being passed on to Express / Fastify / another handler. I did explore another way of fixing this that would avoid that but it felt like it was making the code harder to reason about. I think it's worth further exploration though.
I also see that the node adapter is getting a major refactor so might make sense to wait before bigger changes like that.

Testing

Added a test that sends 30 back-to-back requests to a static page served by the Node.js middleware and Fastify. This triggers the EventEmitter leak warning and is caught by the test. This should help ensure a similar cleanup issue doesn't come up again.

Docs

Internal fix, no docs needed

changeset-bot · 2026-03-03T09:51:27Z

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Latest commit: 3180c38

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codspeed-hq · 2026-03-03T10:08:59Z

Merging this PR will not alter performance

✅ 18 untouched benchmarks

_{Comparing fa-sharp:fix-middleware-leak-2 (3180c38) with main (1d84020)¹}

No successful run was found on main (7e8d0ee) during the generation of this report, so 1d84020 was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

…-2' into fix-middleware-leak-2

ematipico

@matthewp could you look at this please?

ematipico · 2026-03-04T10:57:03Z

packages/astro/src/core/app/node.ts

+ * })
+ * ```
+ */
+export function getAbortControllerCleanup(req?: NodeRequest): (() => void) | undefined {


Why was this function moved? It's hard to tell if there were changes

@ematipico I moved it because it was exported and became part of the public API - that's how the file seemed to be organized (public functions, then internal functions, then deprecated public functions). I can move it back if needed. There shouldn't be any changes to the actual function.

@ematipico I merged the latest changes (including the new node adapter api) and moved that function back for clarity.

original place

ematipico · 2026-03-19T09:28:23Z

~~It seems that e2e tests are failing. They are flaky, but they usually don't fail altogether. @fa-sharp can you look after it?~~ Nevermind, it seems it was an unlucky flaky failure

This PR contains the following updates: | Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) | |---|---|---|---| | [astro](https://astro.build) ([source](https://github.com/withastro/astro/tree/HEAD/packages/astro)) | [`6.0.6` → `6.0.8`](https://renovatebot.com/diffs/npm/astro/6.0.6/6.0.8) | ![age](https://developer.mend.io/api/mc/badges/age/npm/astro/6.0.8?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/npm/astro/6.0.6/6.0.8?slim=true) | --- ### Release Notes <details> <summary>withastro/astro (astro)</summary> ### [`v6.0.8`](https://github.com/withastro/astro/blob/HEAD/packages/astro/CHANGELOG.md#608) [Compare Source](https://github.com/withastro/astro/compare/astro@6.0.7...astro@6.0.8) ##### Patch Changes - [#15978](withastro/astro#15978) [`6d182fe`](withastro/astro@6d182fe) Thanks [@seroperson](https://github.com/seroperson)! - Fixes a bug where Astro Actions didn't properly support nested object properties, causing problems when users used zod functions such as `superRefine` or `discriminatedUnion`. - [#16011](withastro/astro#16011) [`e752170`](withastro/astro@e752170) Thanks [@matthewp](https://github.com/matthewp)! - Fixes a dev server hang on the first request when using the Cloudflare adapter - [#15997](withastro/astro#15997) [`1fddff7`](withastro/astro@1fddff7) Thanks [@ematipico](https://github.com/ematipico)! - Fixes `Astro.rewrite()` failing when the target path contains duplicate slashes (e.g. `//about`). The duplicate slashes are now collapsed before URL parsing, preventing them from being interpreted as a protocol-relative URL. ### [`v6.0.7`](https://github.com/withastro/astro/blob/HEAD/packages/astro/CHANGELOG.md#607) [Compare Source](https://github.com/withastro/astro/compare/astro@6.0.6...astro@6.0.7) ##### Patch Changes - [#15950](withastro/astro#15950) [`acce5e8`](withastro/astro@acce5e8) Thanks [@matthewp](https://github.com/matthewp)! - Fixes a build regression in projects with multiple frontend integrations where `server:defer` server islands could fail at runtime when all pages are prerendered. - [#15988](withastro/astro#15988) [`c93b4a0`](withastro/astro@c93b4a0) Thanks [@ossaidqadri](https://github.com/ossaidqadri)! - Fix styles from dynamically imported components not being injected on first dev server load. - [#15968](withastro/astro#15968) [`3e7a9d5`](withastro/astro@3e7a9d5) Thanks [@chasemccoy](https://github.com/chasemccoy)! - Fixes `renderMarkdown` in custom content loaders not resolving images in markdown content. Images referenced in markdown processed by `renderMarkdown` are now correctly optimized, matching the behavior of the built-in `glob()` loader. - [#15990](withastro/astro#15990) [`1e6017f`](withastro/astro@1e6017f) Thanks [@ematipico](https://github.com/ematipico)! - Fixes an issue where `Astro.currentLocale` would always be the default locale instead of the actual one when using a dynamic route like `[locale].astro` or `[locale]/index.astro`. It now resolves to the correct locale from the URL. - [#15990](withastro/astro#15990) [`1e6017f`](withastro/astro@1e6017f) Thanks [@ematipico](https://github.com/ematipico)! - Fixes an issue where visiting an invalid locale URL (e.g. `/asdf/`) would show the content of a dynamic `[locale]` page with a 404 status code, instead of showing your custom 404 page. Now, the correct 404 page is rendered when the locale in the URL doesn't match any configured locale. - [#15960](withastro/astro#15960) [`1d84020`](withastro/astro@1d84020) Thanks [@matthewp](https://github.com/matthewp)! - Fixes Cloudflare dev server islands with `prerenderEnvironment: 'node'` by sharing the serialized manifest encryption key across dev environments and routing server island requests through the SSR runtime. - [#15735](withastro/astro#15735) [`9685e2d`](withastro/astro@9685e2d) Thanks [@fa-sharp](https://github.com/fa-sharp)! - Fixes an EventEmitter memory leak when serving static pages from Node.js middleware. When using the middleware handler, requests that were being passed on to Express / Fastify (e.g. static files / pre-rendered pages / etc.) weren't cleaning up socket listeners before calling `next()`, causing a memory leak warning. This fix makes sure to run the cleanup before calling `next()`. </details> --- ### Configuration 📅 **Schedule**: Branch creation - At any time (no schedule defined), Automerge - At any time (no schedule defined). 🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied. ♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox. 🔕 **Ignore**: Close this PR and you won't be reminded about this update again. --- - [ ] If you want to rebase/retry this PR, check this box --- This PR has been generated by [Renovate Bot](https://github.com/renovatebot/renovate).  Co-authored-by: Renovate Bot <renovate@zarantonello.dev> Co-committed-by: Renovate Bot <renovate@zarantonello.dev>

add fix and test with comments

126a83e

github-actions bot added pkg: integration Related to any renderer integration (scope) pkg: astro Related to the core `astro` package (scope) labels Mar 3, 2026

add changeset

435a0db

fa-sharp marked this pull request as ready for review March 3, 2026 10:10

fa-sharp and others added 4 commits March 3, 2026 20:36

test: move assertion out of try-catch block

bc33bb6

Merge branch 'main' into fix-middleware-leak-2

0dc8f98

fix docs

292f0a8

Merge remote-tracking branch 'refs/remotes/origin/fix-middleware-leak…

4e64ebe

…-2' into fix-middleware-leak-2

ematipico approved these changes Mar 4, 2026

View reviewed changes

fa-sharp added 3 commits March 5, 2026 19:47

Merge branch 'main' into fix-middleware-leak-2

08193a4

add back comments to getAbortControllerCleanup function, but keep it in

8ca71b6

original place

remove unnecessary test (ssr already tested in node-middleware test)

5fb5a22

ematipico assigned ematipico and matthewp Mar 9, 2026

matthewp approved these changes Mar 9, 2026

View reviewed changes

Merge branch 'main' into fix-middleware-leak-2

3180c38

ematipico merged commit 9685e2d into withastro:main Mar 19, 2026
41 of 44 checks passed

astrobot-houston mentioned this pull request Mar 18, 2026

[ci] release #15985

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fix: EventEmitter memory leak when serving static pages from Node.js middleware#15735

fix: EventEmitter memory leak when serving static pages from Node.js middleware#15735
ematipico merged 10 commits intowithastro:mainfrom
fa-sharp:fix-middleware-leak-2

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fa-sharp commented Mar 3, 2026

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