CLS lost with native Promises in 4.0?

In v4, does CLS work with native Promises, or is Sequelize.Promise currently required?

Instrumenting the usual way:

import Sequelize from 'sequelize';
import cls from 'continuation-local-storage';
Sequelize.cls = cls.createNamespace('transactions');

… this simple example is not executing in a transaction:

this.sequelize.transaction().then(t => {
  return (new ModelName({ some: 'data'})).save();
});

I get the following output:

server_1 | Executing (df667891-2dee-4d1f-b3b1-8c276e5f69d7): START TRANSACTION; server_1 | Executing (default): INSERT INTO tableName (id,createdAt,updatedAt`) VALUES (‘fa9f08ce-48cf-4e2b-b3e1-2127fd6eb9d5’, // cut for brevity

Note:

• The insert is being performed on the default connection (i.e not inside a transaction)
• No implicit commit/rollback - the transaction is left open

I can fix the above by passing in an explicit { transaction }, but then I also need to use try/catch block and wire up t.commit() or t.rollback() manually.

[overlookmotel]

I’m not sure if you can rely on CLS passing correctly with async/await. It all depends on what the polyfill converts it to.

Often with CLS, you test an example like that and it all seems fine, but then once you have multiple async “threads” of execution in flight at the same time it can go pear-shaped, with the CLS context getting mixed up between the “threads”.

Also, native promises do claim to support CLS. But it works slightly differently from my CLS bluebird patch, and also I don’t know how thoroughly it’s tested.

I’d advise using cls-bluebird (once the new version is released, probably in next couple of days) and do this:

return this.sequelize.transaction( Bluebird.coroutine( function*(t) {
  const model = new Model1({
    some: 'data',
  });

  yield model.save();
  yield model2.addDependentModelName(model1);

  return model1;
} ) );

I can pretty much guarantee that’ll work 100%.

[overlookmotel]

All change in the world of CLS with async_hooks now arrived in Node core. But still some kinks need to be worked out in async_hooks itself with how it works with Promises, and it’s going to take a while until lots of npm modules make the necessary changes to support async_hooks.

The CLS implementation in Sequelize (using cls-bluebird) works. But I wouldn’t expect any progress on some of the questions posed above any time soon. Now that async_hooks is here, it’s a matter of rip up most of what came before and re-write from scratch. So that’s going to take time.