Middy cause a timeout with async lambda (but only on AWS, not on my machine)

I had a problem with Middy 1.0.0 and NodeJS 12.x. I was trying to connect to Redshift using dbManager, like this:

const middy = require('@middy/core')
const dbManager = require('@middy/db-manager');

const lambda = middy(async (event, context) => {
    const { db } = context;
    const records = await db.distinct('XXX').from('YYY');

    // print result
    console.log(records);

    // return result
    return {
        'statusCode': 200,
        'body': JSON.stringify(records)
    }
});

lambda    
    .use(dbManager({
        config: {
          client: 'pg',
          connection: {
            host: 'XXX',
            port: '1111',
            schema: 'public',
            user: 'XXX',
            password: 'XXX',
            database: 'XXX'
          }
        }
    }));

module.exports = { lambda }

This was causing Lambda to get stuck, until timeout kill it. I start to searching through the issues of this repo and I’ve found that set context.callbackWaitsForEmptyEventLoop to false. So I introduced the WaitsForEmptyEventLoop middleware and it works but… it only works on my machine! 😃

Yep, joke apart, if I’m executing the sam local invoke FunctionName everything works: the local Lambda invoke correctly the remote redshift and so it ends successfully. But, once I run sam deploy the same code, the same build still produce a timeout when real Lambda is executed.

Why this problem? Any idea?

Bye

[tyvdh]

I too am wrestling with this just now.

Exploring this package atm: https://github.com/middyjs/middy/tree/master/packages/do-not-wait-for-empty-event-loop

Looks like it works when set to:

handler
.use(doNotWaitForEmptyEventLoop({
  runOnBefore: true,
  runOnAfter: true,
  runOnError: true
}))

[tyvdh]

I forgot to close some postgresql pools which caused the event loop to stay full. Adding the do-not-wait-for-empty-event-loop package solved the issue but I really need to ensure I’m closing my pg pools 😄