How to handle multiple concurrent requests with express?

Question

We want to have multiple concurrent requests without using node cluster i.e. if we requests 3 times then we should have the execution ending almost at the same time.

This is sample code:

const execute_select = async () => {
    const jdbcres = new Driver(Conn.MySQL, {host, port, database})
    const d = await jdbcres.sql(‘SELECT * from db.maindb’); // takes 10 seconds to complete

}

app.post(‘/select, (request, response) => {
 execute_select();
 response.send(‘200’);
});

If we execute http://localhost/select 3 times (at the same time), what happens is the following:

1. We immediately get a response back.
2. Each of the requests are blocked at the following line const d = await jdbcres.sql(‘SELECT * from db.maindb’)
3. First one ends within 10 seconds followed by the next one which ends in 10s followed by the next one for a total of about 30seconds.

Is there a way to have calls to /select not waiting for the previous request to end i.e. the total time should be around 10seconds?

My other attempt was to have this in place of the following line: const d = await jdbcres.sql(‘SELECT * from db.maindb’); // takes 10 seconds to complete

/* const result = await new Promise((resolve, reject) => {
   setTimeout(() => {
        const d = jdbcres.sql('SELECT * from db.maindb')
        resolve(d);
    }, 20000);
    });
*/

Please find a list of related pages that I have read:

1. NodeJS Express Async Not Handling More Requests
2. Will using async/await in an express server block all the routes while one is being used?
3. NodeJS Express Async Not Handling More Requests
4. Concurrency in node js express app for get request with setTimeout