Sequelize with sqlite leaks memory according to Jest

What are you doing?

My Jest tests started to crash with “JavaScript heap out of memory”. Enabling --detectLeaks I narrowed that to every test that uses Sequelize. Here’s a minimal repro:

node --expose-gc node_modules/.bin/jest --detectLeaks repro.js

import * as Sequelize from 'sequelize'

// Experiment: pre-requiring dynamic imports didn't increase memory during tests, but not the behavior of "JavaScript heap out of memory" error.
require('sqlite3')
require('sequelize/lib/dialects/sqlite')

const getMemory = () => {
    global.gc()
    process.memoryUsage().heapUsed / Math.pow(1024, 2)
}

test.each(['./db.sqlite', './db2.sqlite', undefined, undefined])('Sequelize should not leak', (storage) => {
    const mem = getMemory()
    new Sequelize('Leaker', 'tester', 'bestpassword', {dialect: 'sqlite', storage})
    console.log('Memory (MB):', mem.toFixed(2), '+', (getMemory() - mem).toFixed(2))
})

Furthermore, I found out that the problem is a “sqlite” dialect, because if I add return before any of the following lines, the Jest’s “Your test suite is leaking memory.” is gone and repro succeeds.

this.dialect = new Dialect(this);  // node_modules/sequelize/lib/sequelize.js
this.connectionManager = new ConnectionManager(this, sequelize);  // node_modules/sequelize/lib/dialects/sqlite/index.js
this.lib = require('sqlite3').verbose();  // node_modules/sequelize/lib/dialects/sqlite/connection-manager.js

What do you expect to happen?

I expect the repro above to succeed.

What is actually happening?

The repro above throws “JavaScript heap out of memory” by Jest.

node: v8.15.0 Jest: 24.5.0 Dialect: sqlite Dialect version: sqlite3@4.0.6 Database version: n/a Sequelize version: sequelize@4.39.0 Tested with latest release: Yes

P.S. Don’t know if this is either Sequelize or Jest bug, so I posted at both.

• https://github.com/sequelize/sequelize/issues/10640
• https://github.com/facebook/jest/issues/8229

[papb]

Can anyone please test if this isn’t an issue with the sqlite3 package itself? In other words, what happens if you run Jest with sqlite3 directly (not Sequelize)? Thanks

[ephys]

I’m not seeing any calls to Sequelize#close, try adding that and see if the issue resolves itself