Where is bottlenect in sentry onpremise?

[BYK]

@potter7050

Are both Redis and Workers used in 20.x.x versions other than 9.1.2? If used, what role does it play?

Yes they are. In the on-premise repo we use Redis as a message broker for Celery (workers). Workers are responsible for post-processing the events and attaching various extra context to them.