Logger::Formatter aware of Thread.current for JRuby

current_thread_aware_formatter.rb

require 'jruby'
class CurrentThreadAwareFormatter < Logger::Formatter
 FORMAT = "%s [%5s] {%s} -- %s\n".freeze
 def call(severity, time, progname, msg)
   thread = Thread.current
   thread_id = JRuby.reference(thread).getNativeThread.to_s
   thread_id << ' ' << ( thread[:name] || thread.to_s )
   FORMAT % [format_datetime(time), severity, thread_id, msg2str(msg)]
 end
end
# ...
logger.formatter = CurrentThreadAwareFormatter.new