--detectOpenHandles shouldn't report unreferenced workers. #11707
Description
🐛 Bug Report
Node.js workers have an .unref() method that, when called, makes them not prevent the main thread from exiting. It's similar to setTimeout().unref().
If a worker has been .unref()ed, Jest shouldn't report it in --detectOpenHandles. This is siilar to #8941
To Reproduce
I have two file: test.js and worker.js (I tested them in a bigger repository; if needed I'll create a self-contained repo).
test.js:
const { Worker } = require("worker_threads");
if (typeof describe === "undefined") {
globalThis.describe = globalThis.it = (name, fn) => fn();
globalThis.expect = () => ({
toBe() {
console.log("DONE");
},
});
}
describe("test", () => {
it("test", () => {
const worker = new Worker(__dirname + "/worker.js");
worker.unref();
expect(1).toBe(1);
});
});worker.js:
setInterval(() => {
console.log("XX");
}, 1000);Expected behavior
When running node test.js it logs "DONE", and the process exits immediately (without logging "XX").
When running test.js with Jest, it (correctly) logs
PASS eslint/babel-eslint-parser/test/worker.js
test
✓ test (2 ms)
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 0.588 s, estimated 1 s
and then exits immediately.
When running test.js with Jest and --detectOpenHandles, it logs
Jest has detected the following 1 open handle potentially keeping Jest from exiting:
● WORKER
15 | describe("test", () => {
16 | it("test", () => {
> 17 | const worker = new Worker(__dirname + "/helpers/worker.cjs");
| ^
18 | worker.unref();
19 |
20 | expect(1).toBe(1);
at Object.<anonymous> (eslint/babel-eslint-parser/test/worker.js:17:20)
at TestScheduler.scheduleTests (node_modules/@jest/core/build/TestScheduler.js:347:13)
at runJest (node_modules/@jest/core/build/runJest.js:387:19)
at _run10000 (node_modules/@jest/core/build/cli/index.js:408:7)
at runCLI (node_modules/@jest/core/build/cli/index.js:261:3)
This worker doesn't prevent the process from exiting, so it shouldn't be reported. It should still be reported if you delete worker.unref() from my example.
envinfo
System:
OS: Linux 5.11 Ubuntu 21.04 (Hirsute Hippo)
CPU: (12) x64 Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
Binaries:
Node: 16.3.0 - /usr/local/bin/node
Yarn: 2.4.1-git.20210125.0f31e6910 - /usr/bin/yarn
npm: 7.9.0 - ~/.npm-global/bin/npm
npmPackages:
jest: ^27.0.0 => 27.0.1
Context
In the Babel repo we have a test where 90% of the times every test passes, but then Jest waits without ever exiting (and CircleCI kills it after 10 mins without output, marking it as failed). I tried using the --detectOpenHandles option, but it only reports a worker for which I was calling worker.unref() (CircleCI output).