fetch + signal memory leak

[exe-dealer]

deno v1.27.0

const { signal } = new AbortController();
const kAbortAlgos = Object.getOwnPropertySymbols(signal).find(s => String(s) == 'Symbol([[abortAlgos]])');

console.log('abortAlgos size before', signal[kAbortAlgos]?.size);
for (let i = 0; i < 100; i++) {
  const resp = await fetch('data:,', { signal });
  await resp.arrayBuffer();
}
console.log('abortAlgos size after', signal[kAbortAlgos].size);

stdout:

abortAlgos size before undefined
abortAlgos size after 100

[exe-dealer]

deno/ext/web/03_abort_signal.js

Lines 182 to 183 in dbcbf53

	parentSignal[add](() =>
	followingSignal[signalAbort](parentSignal.reason)

this callback is added to signal but never removed. If signal lifetime is the same as application lifetime, then memory usage grows until deno crash.

[nktpro]

I could also confirm this issue still persists as of the latest 1.33.2 release.

[lucab]

The fetch spec related to this has been updated by whatwg/fetch#1646 in the meanwhile, so the proper fix for this will likely follow after #18944 is done.

[lucab]

Fixed as part of #21087.