Workaround for JRuby's timeout not working well with IO.popen

jruby_timeout.rb

# Workaround for IO.popen.readlines being allowed to block indefinitely even if
# wrapped in a Timeout::timeout call.
#
# Test case:
#  $ time jruby -rtimeout -e "timeout(1) { IO.popen('sleep 10').readlines }"
require 'jruby'

module Timeout
  def self.timeout(sec, klass=nil)
    return yield(sec) if sec == nil or sec.zero?
    thread = Thread.new { yield(sec) }

    if thread.join(seconds).nil?
      java_thread = JRuby.reference(thread)
      thread.kill
      java_thread.native_thread.interrupt
      thread.join(0.15)
      raise (klass || Error), 'execution expired'
    else
      thread.value
    end
  end
end

include Timeout

Note: one problem with the above hack is that interrupting a blocking Java IO read (as is happening here) generally closes the underlying stream and it can no longer be used. That's why we've gone back and forth on whether to do a hard Thread interrupt or just block.