Here's an example from the circleci incident

and a good analysis by a flicker engineer who ran into similar issues

CircleCI and Flickr are both pretty big systems. There are tons of businesses that will never operate at that scale.

	▲	gregors an hour ago \| parent [-]
		I don't disagree with that call out. However, we've been through these discussions many times over the years. The solid queue of yesteryear was delayed_job which was originally created by Shopify's CEO. https://github.com/tobi/delayed_job Shopify however grew (as many others) and we saw a host of blog posts and talks about moving away from DB queues to Redis, RabbitMQ, Kafka etc. We saw posts about moving from Resque to SideKiq etc. All this to day storing a task queue in the db has always been the naive approach. Engineers absolutely shouldn't be shocked that approach isn't viable at higher workloads.