fix(server-runtime: fix request signal not aborting after request is garbage collected

[jvaill]

Closes: #9976 (comment) Edit: There appears to be a different bug with signals not working at all in production.

Update (Sep 26)

In development, it appears that globals aren't being automatically installed and Request with node ends up coming from undici. undici currently has a bug where parent signals aren't properly followed: nodejs/node#55428

In production, globals are installed and Request comes from web-fetch. This version of Request does not have the above issue.

It seems like globals should be installed in development as well? Manually invoking installGlobals() changes the Request object and solves this issue.

Original:

Testing Strategy:

Add remix-utils and the following routes. Start the dev server and open /time in a bunch of different tabs. Refresh the tabs randomly, close them, create new ones, etc, and eventually you'll trigger the GC in the right way where SSE connection closed ${number of open conns} will be logged to the console with the number of open connections being greater than the number of open tabs. A good way to see if you've triggered this is just to close all of them and see if the logged connection count is greater than 0.

routes/sse.time.ts

import { LoaderFunctionArgs } from "@remix-run/node"
import { eventStream } from "remix-utils/sse/server"

let conns = 0;

export async function loader({ request }: LoaderFunctionArgs) {
  conns++;
  return eventStream(request.signal, function setup(send) {
    const timer = setInterval(() => {
      send({ event: "time", data: new Date().toLocaleTimeString() })
    }, 1000)

    return function clear() {
      conns--;
      console.log("SSE connection closed", conns);
      clearInterval(timer)
    }
  })

routes/time.tsx

import { useEventSource } from "remix-utils/sse/react"

export default Route(){
  let time = useEventSource("/sse/time", { event: "time" })
  if (!time) {
    time = new Date().toLocaleTimeString()
  }

return <p>{time}</p>

[changeset-bot]

🦋 Changeset detected

Latest commit: aaab009

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 16 packages

Name	Type
@remix-run/server-runtime	Patch
@remix-run/cloudflare	Patch
@remix-run/deno	Patch
@remix-run/dev	Patch
@remix-run/node	Patch
@remix-run/react	Patch
@remix-run/testing	Patch
@remix-run/cloudflare-pages	Patch
@remix-run/cloudflare-workers	Patch
@remix-run/architect	Patch
@remix-run/express	Patch
@remix-run/serve	Patch
create-remix	Patch
remix	Patch
@remix-run/css-bundle	Patch
@remix-run/eslint-config	Patch

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[remix-cla-bot]

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[jvaill]

Fyi - the underlying problem appears to be a bug in undici:

nodejs/node#55428

[brophdawg11]

It seems like globals should be installed in development as well? Manually invoking installGlobals() changes the Request object and solves this issue.

FWIW we are deprecating the @remix-run/web-fetch package in favor of using the built-in fetch on Node 20 and above - something you can opt-into via installGlobals({ nativeFetch: true }) and is usually done when you opt into Single Fetch (see https://remix.run/docs/en/main/guides/single-fetch#breaking-changes).

For now, it looks like there is some traction on the node/undici end so do we think they'll be getting a fix out anytime soon? It would be nice not to have to put this type of workaround/hack into the Remix codebase to fix a bug in undici/node...

[jvaill]

@brophdawg11 Another update on this - (IIRC, been a few weeks) at first I thought this was going to fix signals in production, but it seems like that's an entirely different bug altogether. When signals are working (i.e., in development), this fixes signals sporadically not being aborted due to GC.

I gave up on getting signals to work and ended up switching from SSE to websockets 😅

[Eiley2]

@brophdawg11 Another update on this - (IIRC, been a few weeks) at first I thought this was going to fix signals in production, but it seems like that's an entirely different bug altogether. When signals are working (i.e., in development), this fixes signals sporadically not being aborted due to GC.

I gave up on getting signals to work and ended up switching from SSE to websockets 😅

Did you implement your own server with Express and Remix? Or what did you use? Considering to do the same tbh

[mkromann]

Is it correct to say that SSEs are not working right now in Remix? I have been trying the last few days to find a workaround to this but been unable. We are starting up a new project and this is a curveball. It would be sad to go another route than Remix!

These issues are also reported here:
sergiodxa/remix-utils#317
dan-cooke/remix-sse#27

[mkromann]

@brophdawg11 Have you considered the path forward regarding this issue? Is this a waiting thing, or something you can/will patch?

[jvaill]

@brophdawg11 Another update on this - (IIRC, been a few weeks) at first I thought this was going to fix signals in production, but it seems like that's an entirely different bug altogether. When signals are working (i.e., in development), this fixes signals sporadically not being aborted due to GC.
I gave up on getting signals to work and ended up switching from SSE to websockets 😅

Did you implement your own server with Express and Remix? Or what did you use? Considering to do the same tbh

I ended up adding a separate service to handle websockets. Basically, it uses createServer (node:http) and upgrade the connection to a websocket via WebSocketServer (ws). I use redis pub/sub to trigger messages from the remix app that get picked up by the service and proxied to the client. Might be a bit overly complex depending on your needs.