Rails.logger に 時間/PID/LEVEL 追記するやつ

application.rb

config.logger = Logger.new(config.paths["log"].first)
config.logger.formatter = Logger::Formatter.new

logger_formatter.rb

class Logger
  class Formatter
    def call(severity, time, progname, msg)
      format = "[%s][%d][%s] %s\n"
      messages = msg2str(msg)

      [].tap do |array|
        messages.each_line do |message|
          array << (format % ["#{time.strftime('%Y-%m-%d %H:%M:%S')}.#{'%06d' % time.usec.to_s}", $$, severity, message.chomp])
        end
      end.join
    end
  end
end

sample.log

[2013-10-02 13:07:04.812954][76244][INFO] Started GET "/" for 127.0.0.1 at 2013-10-02 13:07:04 +0900
[2013-10-02 13:07:04.880362][76244][INFO] Processing by RootController#index as HTML
[2013-10-02 13:07:04.957657][76244][DEBUG]   User Load (0.2ms)  SELECT `users`.* FROM `users` ORDER BY id desc LIMIT 25
[2013-10-02 13:07:05.013784][76244][INFO]   Rendered root/index.html.erb within layouts/application (31.2ms)
[2013-10-02 13:07:05.193171][76244][INFO]   Rendered shared/_footer.html.erb (0.5ms)