Get a trace from a 'stack too deep' error in Rails

trace.rb

$enable_tracing = false
#$trace_out = File.open(Rails.root + 'trace.txt', 'w')

set_trace_func proc { |event, file, line, id, binding, classname|
  if $enable_tracing && event == 'call'
    #$trace_out.puts "#{file}:#{line} #{classname}##{id}"
    raise "crash me" if caller_locations.length > 500
  end
}

$enable_tracing = true