sequelizeTransactionPoolSize.js

/*
$ node sequelizeTransactionPoolSize.js 
Started promises { count: 5 }
Executing (1cd366d4-a412-4a87-9185-0261f208169b): START TRANSACTION;
Executing (d9eadf8c-7407-4653-9a71-c3f83aee9ca2): START TRANSACTION;
Executing (d1c4e9e1-0fdf-4284-8cfc-9f0f60cc0ff1): START TRANSACTION;
Executing (c3ea6d09-b3e9-44dd-b277-1ac715f9c942): START TRANSACTION;
Executing (89824a8c-766d-490f-9b65-d0baab9b2030): START TRANSACTION;

it just hangs
*/

const { Sequelize } = require('sequelize');

const sequelize = new Sequelize('postgres://postgres@localhost:5432/postgres', {
  seederStorage: 'sequelize',
  dialect: 'postgres',
  define: {
    timestamps: false,
  },
  // logging: false,
  pool: {
    max: 5,
  },
});

async function query() {
  await sequelize.transaction(async (transaction) => {
    const one = await sequelize.query('SELECT 1');
    console.log('Queried one', one);
  });
}

async function concurrentQuery({ count = 1 }) {
  const promises = [];
  for (let i = 0; i < count; i++) {
    promises.push(query());
  }
  console.log('Started promises', { count: promises.length });
  await Promise.all(promises);
}

function parseArgs(argv = process.argv) {
  return argv.slice(argv.findIndex((x) => x === __filename) + 1);
}

const args = parseArgs();
const count = parseInt(args[0]) || 5;

concurrentQuery({ count })
  .then(() => {
    console.log('result', 'pool config', sequelize.config.pool);
  })
  .catch((err) => {
    console.error(err);
  })
  .finally(() => {
    sequelize.close()
      .then(() => {
        console.log('Closed sequelize');
      })
      .catch((err) => {
        console.error(err);
      });
  });