Example for https://github.com/oracle/node-oracledb/issues/1231

issue1231.js

'use strict';

process.env.UV_THREADPOOL_SIZE = 5;
const myPoolSize =               5;  // poolMin & poolMax;
const numStmts =                 5;  // number of statements to run in parallel

console.log('UV_THREADPOOL_SIZE       :', process.env.UV_THREADPOOL_SIZE );
console.log('poolMin & poolMax        :', myPoolSize);
console.log('number of selects to run :', numStmts);

process.env.ORA_SDTZ = 'UTC';

const oracledb = require('oracledb');
const config = require('./dbconfig.js');

let executeCount = 0;

async function executeQuery(query) {
  const c = executeCount++;
  const startTime = Date.now();
  console.log(`execute #${c}.           Started at`, startTime);
  let connection;
  try {
    connection = await oracledb.getConnection();
    const result = await connection.execute(query);
    //console.log(result.rows[0]);
    const endTime = Date.now();
    console.log(`execute #${c} took ${endTime - startTime} ms.  Ended at`, endTime);
    return result;
  } catch (err) {
    console.log(err);
  } finally {
    if (connection) {
      await connection.close();
    }
  }
}

async function run() {
  await oracledb.createPool({
    user: config.user,
    password: config.password,
    connectString: config.connectString,
    poolMax: myPoolSize,
    poolMin: myPoolSize,
    poolIncrement: 0
  });

  console.log('Pool creation complete');

  let queries = new Array(numStmts);
  queries.fill('select current_timestamp from dual');
  queries.map(executeQuery);
  await Promise.all(queries);
}

async function closePoolAndExit() {
  console.log("\nTerminating");
  try {
    // Get the pool from the pool cache and close it
    // If this hangs, you may need DISABLE_OOB=ON in a sqlnet.ora file
    await oracledb.getPool().close(0);
    console.log("Pool closed");
    process.exit(0);
  } catch(err) {
    console.error(err.message);
    process.exit(1);
  }
}

process
  .once('SIGTERM', closePoolAndExit)
  .once('SIGINT',  closePoolAndExit);

run();