Hacky script to convert a Rails log file to timestamp-render time .tsv

rails_log_to_tsv.rb

IN  = '/tmp/production.log'
OUT = '/tmp/render_time.tsv'

render_vals = File.read(IN).split("\n\n").map do |lines|
  # render time
  m = lines.match(/^Completed in (\d+)ms/)
  next unless m
  render_time = m.captures[0].to_i
  # action and timestamp
  m = lines.match(/^Processing (\S*) \(for \S* at ([^)]*)\)/)
  next unless m
  action, timestamp = m.captures[0], m.captures[1]
  [action, timestamp, render_time]
end.compact

File.open(OUT, "w") do |f|
  f.write(render_vals.map{|tuple| tuple.join("\t")}.join("\n"))
end