Question

I am getting the SystemStackError in a Rails 3 app.

All the information I have is useless one line of a stacktrace (taken from the log):

SystemStackError (stack level too deep):
  activesupport (3.2.3) lib/active_support/callbacks.rb:409

So the question is how do I see the full stack trace?

NOTE: I don’t care about why this happens, all I want is to see is where it happens.

Using: Rails 3.2.3, Unicorn.

Thanks.

Answer 1

That’s pretty complex code in lib/active_support/callbacks.rb, but it looks like it is applying various callbacks: :before, :after, :around, to be precise.

You might try placing an old fashioned “puts before #{name}” before line 426 and seeing what you get.

Equally, could be that the entire stack trace is inside the rails stack, and it is being filtered out by the default backtrace_filter. Setting that backtrace_filter off might let you see the stack and get a debugging clue. See config/initializers/backtrace_silencers.rb and uncomment:

Rails.backtrace_cleaner.remove_silencers!