DRb TimerIdConv cleanup

[mkanoor]

https://bugzilla.redhat.com/show_bug.cgi?id=1321934

The TimerIdConv thread was not being terminated after a method ends.
The TimerIdConv thread sleeps for a hour before it GC's the objects

Here is an example of the thread count growth, but simplified outside of automate

require 'drb'
require 'drb/timeridconv'

100.times do
  # setup the drb server with a one second timer
  # creates a new thread that never dies
  timer = DRb::TimerIdConv.new(5)

  service = DRb.start_service("druby://127.0.0.1:0", nil, :idconv => timer)

  # ... some code that uses the DRb service

  # stop the drb server now that we're done with it
  service.stop_service

  # Below is ugly code that kills the timer thread.  Without the code below, the
  # thread stays alive forever.  This should have a public API.
  # It would be nice if DRb.start_service
  # accepted a :timer_idconv => 5 option that would create the timer thread itself
  # and was responsible for killing this thread when calling stop_service.

  # holder = timer.instance_variable_get(:@holder)
  # keeper = holder.instance_variable_get(:@keeper) if holder
  # keeper.kill if keeper
  puts Thread.list.length
  sleep 2
end

Thread count slowly rises:

2
3
4
5
6
7
8
9

Opened a ruby bug to see if we can fix this in ruby or through a cleaner API: https://bugs.ruby-lang.org/issues/12342 ?

[mkanoor]

@jrafanie @dmetzger57

Please review

[jrafanie]

I'm looking to see if there's a better way.

[jrafanie]

Please link to this for context and this so we can clean this up if they fix it in 2.3.2 or later. Please put a comment about what we're doing because it's not obvious at all.

[jrafanie]

@mkanoor Can you review this: https://bugs.ruby-lang.org/issues/12342 ?

[miq-bot]

Checked commit mkanoor@1428c1e with ruby 2.2.3, rubocop 0.37.2, and haml-lint 0.16.1
1 file checked, 0 offenses detected
Everything looks good. 🍪