`#stop` does not actually stop watching

[graywolf-at-work]

I create bunch of listeners on temp folders:

$listeners = []
$tempdirs = []
1.upto(5).do
  $tempdirs << Dir.mktmpdir
  $listeners << Listen.to($tempdirs.last) do
    # does not matter
  end
end

I run my rspec suite and want to stop everything

$listeners.each(&:stop)
$tempdirs.each { |f| FileUtils.rmdir f }

However, from time to time (under heavy load almost every time) I get

E, [2018-09-11T13:55:34.462726 #26239] ERROR -- : exception while processing events: No such file or directory @ realpath_rec - /tmp/d20180911-26239-11dhxny Backtrace:
 -- /home/user/showmax/gem/XXX/lib/XXX/rack/health.rb:22:in `realdirpath'
 -- /home/user/showmax/gem/XXX/lib/XXX/rack/health.rb:22:in `realdirpath'
 -- /home/user/showmax/gem/XXX/lib/XXX/rack/health.rb:22:in `block in initialize'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/event/config.rb:23:in `call'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/event/processor.rb:115:in `_process_changes'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/event/processor.rb:19:in `block in loop_for'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/event/processor.rb:15:in `loop'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/event/processor.rb:15:in `loop_for'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/event/loop.rb:84:in `_wait_for_changes'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/event/loop.rb:42:in `block in setup'
 -- /home/user/.rvm/gems/ruby-2.4.4@XXX/gems/listen-3.1.5/lib/listen/internals/thread_pool.rb:6:in `block in add'

When I add some logging into the code

$listeners = []
$tempdirs = []
1.upto(5).do
  $tempdirs << Dir.mktmpdir
  STDERR.puts "CREATED: #{$tempdirs.last}"
  $listeners << Listen.to($tempdirs.last) do
    # does not matter
  end
end

...

$listeners.each(&:stop)
STDERR.puts "STOPPED"
$tempdirs.each { |f| FileUtils.rmdir f }

I see this order in console:

CREATED ...
CREATED ...
...
STOPPED
E, [2018-09-11T13:55:34.462726 #26239] ERROR -- : exception while processing events: No such file or directory @ realpath_rec - /tmp/d20180911-26239-11dhxny Backtrace:
...

So the watching seems to continue even after #stop call :/

[graywolf-at-work]

fuckup on my end, sorry