memory leak with timers

[kostya]

this program eats 2Gb in 10 hours. i think this related somehow to gem timers (also there was a leak in it before #455). ruby 2.4.1p111, celluloid: "0.17.3", timers: "4.1.2", Ubuntu 12.04.1 LTS

require 'celluloid'

class A
  include Celluloid

  def initialize
    @timer = every(0.5) {}
  end

  def stop
    @timer.cancel
    terminate
  end
end

p Celluloid::VERSION
p Timers::VERSION

loop do
  actors = Array.new(50) { A.new }
  sleep 10.0
  actors.each &:stop
end

[kostya]

actually seems this is not about timers, this leak also (1Gb in 5 hours):

require 'bundler/setup'
require 'celluloid'

class A
  include Celluloid

  def initialize
  end

  def stop
    terminate
  end
end

p Celluloid::VERSION
p Timers::VERSION

loop do
  actors = Array.new(50) { A.new }
  sleep 10.0
  actors.each &:stop
end

[perlun]

FWIW, I am also seeing similar but not entirely identical behavior with Celluloid Notifications. Only on JRuby, works fine on MRI.

The script below will use up about 4 GiB in 5 minutes. Some of this will be reclaimed on GC, but even so, there is still an unreasonably large amount of memory being retained.

require 'bundler/setup'
require 'celluloid'
require 'celluloid/autostart'

class Subscriber
  include Celluloid
  include Celluloid::Notifications

  def initialize
    subscribe('errors', :error)
    puts 'Subscriber initialized'
  end

  def error(topic, data)
    #puts 'got it'
  end
end

class Publisher
  extend Celluloid::Notifications

  def self.publish_message(error)
    publish(
      'errors',
      error: error
    )
  end
end

p Celluloid::VERSION

subscriber = Subscriber.new

loop do
  Publisher.publish_message('dummy error')
end

Are we using Celluloid Notifications in the completely wrong way or is there indeed a bug in Celluloid/JRuby here?

(A longer writeup about how I landed here: http://perlun.eu.org/en/2018/06/28/jruby-memory-leak-in-production)