AbortSignal.any() stops following a timeout signal once a listener is added to the timeout and removed, so the composite never aborts after a GC #66610

Version

v26.10.0 and v26.11.1.

Platform

Linux arm64.

Subsystem

lib (abortcontroller)

What steps will reproduce the bug?

Run node --expose-gc repro.mjs:

// node --expose-gc e1.mjs
const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
for (const touch of [false, true]) {
  const composite = (() => {
    const timeout = AbortSignal.timeout(100);
    const made = AbortSignal.any([timeout]);
    if (touch) {
      const listener = () => {};
      timeout.addEventListener("abort", listener);
      timeout.removeEventListener("abort", listener);
    }
    return made;
  })();
  composite.addEventListener("abort", () => {});
  await sleep(10);
  globalThis.gc();
  await sleep(300);
  console.log(`listener added and removed on the timeout: ${touch}; composite aborted: ${composite.aborted}`);
}

How often does it reproduce? Is there a required condition?

Always: 3 of 3 runs on each version. The timeout must have had a listener that was then removed, and a garbage collection must run before it fires.

What is the expected behavior? Why is that the expected behavior?

listener added and removed on the timeout: true; composite aborted: true. A composite aborts when one of its sources does, whatever listeners came and went on the source.

What do you see instead?

composite aborted: false: the timeout is collected before it fires, so the composite never aborts.

Additional information

#57867 keeps a timeout that AbortSignal.any() follows in gcPersistentSignals. Removing the timeout's last abort listener seems to delete it from that set while a composite still follows it. We hit this in code that hands a timeout to AbortSignal.any() and also waits on the timeout itself, for example with timers/promises' setTimeout(ms, value, { signal }), which adds a listener and removes it.