expensive function tracing

set_trace_func.rb

set_trace_func proc { |event, file, line, id, binding, classname|
  #cpu = `ps auxfh | grep #{$$} | grep -v tracer | grep -v grep | awk '{print $3}'`.strip
  fid ||= File.open("/tmp/tracer.#{$$}", 'a+') 
  fid.puts "[%s][%s] %8s %s:%-2d %10s %8s\n" % [Time.now, '', event, file, line, id, classname] if file.match(/srv/) && !file.match(/vendor\/|usr\/local\/lib/)
}