Ruby Passenger + Ngnix = hanging. What could be the reason?

Question

Ruby on Rails

The server has two instances of Passenger + Ngnix installed and running on different ports. One for the production environment, the second for the test environment.
Until recently, everything was fine. But since about two weeks ago, the test environment began to hang every 2-3 days.
It looks like this:
When accessing the server, it is silent for a long time and says 504 Gateway Timeout. However, there is nothing in the logs. I do a re-start, and everything works correctly.
Since the production environment works stably, I suppose the problem is some bugs in the code that is constantly being developed and tested on the test environment. But I can not understand what is the reason - everything is clean in the logs.
What are Passenger advanced monitoring tools? Maybe there are some detailed logs or something? What can be advised in such a situation?
Thanks in advance!

Answer 1

I'll try to guess, do you have an application under passenger there? enable logging and look for errors in development.log (production.log for production environment). most likely the request goes to the application and gets stuck there.