Memory leak in knex v0.13.0

[badwulfy]

Hi,

When importing, then destroying, then reset modules a lot of times with jest, I have some warning about memory leak MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 SIGABRT listeners added. Use emitter.setMaxListeners() to increase limit

I think that destroy() leave listener that should be removed.

Here is the (useless) code to reproduce the issue :

//@flow

import k from 'knex';
import path from 'path';

const config = {
  client: 'sqlite3',
  connection: {
    filename: path.join(__dirname, './database.sqlite'),
  },
  pool: {
    min: 1,
    max: 1,
  },
  migrations: {
    tableName: 'knex_migrations',
  },
  useNullAsDefault: true,
  timezone: 'UTC',
};

let knex;

describe('pppppppppp', () => {
  beforeEach(async () => {
    jest.resetModules();
    knex = k(config);
  });

  afterEach(async () => {
    await knex.destroy();
  });

  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
  test('test', () => {});
});

the output :

Is it a bad use or a bug ?
Thanks in advance.

[badwulfy]

it seems to be the same issue as #2106

[elhigu]

Thanks for report, would be great to add this kind of test (and fixes ofc) to test suite.

[wubzz]

Can be reproduced as long as jest.resetModules() is called. I tested this example against branch of #2128 and there the warning no longer exists. So presumably that PR fixes the memory leak by upgrading generic-pool version.

[fl0w]

I've experienced this when using jest specifically myself. I'm wondering if this simply isn't a knex issue, but rather a jest issue. I do not experience equivalent issues in a project using mocha (while completely different projects, the setup is quite similar, both testing API endpoints using supertest/koa2/objection)

[fl0w]

@kiralex if you explicitly call jest.clearAllTimers() in afterEach, does it fix it for you?

[badwulfy]

I will try. ☺️ I will give you my feedback after. Le 27 juil. 2017 23:50, "Martin Iwanowski" <notifications@github.com> a écrit :

…

@kiralex <https://github.com/kiralex> if you explicitly call jest.clearAllTimers() in afterEach, does it fix it for you? — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#2165 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AC51o8tAsuaF1Qg7RwKy0EWdMSfAZqqtks5sSQYUgaJpZM4OePlm> .

[badwulfy]

@fl0w nop, it does not fix the issue

[elhigu]

@kiralex Does it leak when running initialization and destroy sequence without jest?

[wubzz]

From my previous tests this should be fixed by #2208, so closing this for now. If it's still an issue in upcoming 0.14, feel free to reopen.