Ruby on Rails: Async Query Instrumentation Fix and Auth Generator Polish
Today we're diving into a crucial async query instrumentation bug fix by rosa that was affecting request logging, plus improvements to the authentication generator for apps that skip Action Mailer. The Rails core team merged 4 pull requests with some duplicate fixes that show how important this instrumentation issue was.
Duration: PT3M55S
Episode overview
This episode is a short developer briefing from Ruby on Rails.
It explains recent repository work in plain language.
- Show: Ruby on Rails
- Published: 2026-03-12T10:19:04Z
- Audio duration: PT3M55S
Transcript excerpt
This excerpt keeps the crawler page concise. Listen to the episode or use the RSS feed for the full update.
Hey there, Rails developers! Welcome back to another episode of the Ruby on Rails podcast. I'm your host, and it's March 12th, 2026. Grab your favorite beverage because we've got some really interesting fixes to talk about today that might just solve some mysterious issues you've been having in production.
So picture this scenario - you're using async queries in your Rails app, which is awesome for performance, right? You've got `async_load` and `async_pick` working beautifully with the global thread pool executor. Everything seems great until you notice something weird happening. Some of your requests just... aren't…
Well, if that sounds familiar, rosa just became your hero today. They identified and fixed a really sneaky bug in how Rails handles instrumenters with async queries. Here's what was happening - and this is one of those bugs that really shows how complex modern web applications can be.
When you're using async queries with the global thread pool, Rails has a fallback policy called "caller runs." Basically, if the thread pool gets saturated and all the background threads are busy, the async task falls back to running on your main request thread. Totally reasonable, right?
B…