Thread dump-ing for JRuby (using MX)

thread_dump.rb

require 'java'

module ThreadDump

  def self.thread_dump(output = nil)
    output ||= ''
	  thread_mbean = java.lang.management.ManagementFactory.getThreadMXBean
	  thread_ids = thread_mbean.getAllThreadIds # long[]
	  threads = thread_mbean.getThreadInfo(thread_ids, false, false) # ThreadInfo[]
    threads.each do |thread_info|
      next if thread_info.nil? # not an active thread

      output << '"' << thread_info.getThreadName
      output << '" tid=' << thread_info.getThreadId.to_s
      output << ' ' << thread_info.getThreadState.toString

      if thread_info.getLockName
        output << ' on lock=' << thread_info.getLockName
      end
      output << ' (suspended)' if thread_info.isSuspended
      output << ' (running in native)' if thread_info.isInNative

      stackTrace = thread_info.getStackTrace # StackTraceElement[]
      if stackTrace.length > 0; ste = stackTrace[0]
        output << " in #{ste.getClassName}.#{ste.getMethodName}()"
      end

      output << "\n"

      if thread_info.getLockOwnerName
        output << "\t owned by " << thread_info.getLockOwnerName
        output << " Id=" << thread_info.getLockOwnerId.to_s
        output << "\n"
      end

      for ste in stackTrace
        output << "\tat #{ste.toString}\n"
      end
    end
    output
  end

end