I am using Rails 4.2 and Ruby 2.2.0. Recently, I have noticed that my app will hang for long periods of time when a certain worker is working. This is an app that has been under development for several years and I have never seen this sort of hanging behavior before (nor am I unfortunately completely aware of what changes I've made since it was last not hanging).
What I mean by "hang" is: No pages will load (no controllers can be reached, and even the default homepage which is basically a static page won't load). None of my logs will update. Standard output is not being written to. The application also has many background worker processes (managed by Resque), which also appear to be hung.
I have looked at top and netstat and various other Unix utilities and I don't see anything alarming there, either.
Finally, I'm not sure if it's worth mentioning but this application is running via Foreman on an EC2 instance.
EDIT: I don't believe that it is query related, because nothing abnormal shows up on top. Also, I'm a little inexperienced with rails, but each job has its own entry in the process table, if that helps.