Cigri fails to start with ruby 2.1: code is deadlockable

[bzizou]

Ruby 2 checks for deadlockable code and the way we are using signal handlers, with logging inside handlers is in this case:
log writing failed. can't be called from trap context
/usr/lib/ruby/2.1.0/monitor.rb:185:in lock': can't be called from trap context (ThreadError) from /usr/lib/ruby/2.1.0/monitor.rb:185:inmon_enter'
from /usr/lib/ruby/2.1.0/monitor.rb:209:in mon_synchronize' from /usr/lib/ruby/vendor_ruby/dbi.rb:231:inload_driver'
from /usr/lib/ruby/vendor_ruby/dbi.rb:149:in _get_full_driver' from /usr/lib/ruby/vendor_ruby/dbi.rb:134:inconnect'
from /usr/local/share/cigri/lib/cigri-iolib.rb:44:in db_connect' from /usr/local/share/cigri/lib/cigri-iolib.rb:1606:ininitialize'
from /usr/local/share/cigri/lib/cigri-eventlib.rb:78:in initialize' from /usr/local/share/cigri/modules/judas.rb:90:innew'
from /usr/local/share/cigri/modules/judas.rb:90:in notify' from /usr/local/share/cigri/modules/judas.rb:107:inblock in

'
from /usr/local/share/cigri/modules/judas.rb:113:in call' from /usr/local/share/cigri/modules/judas.rb:113:insleep'
from /usr/local/share/cigri/modules/judas.rb:113:in `'

A simple workaround should be to create a Thread for all logger inside a trap, but I'm not sure that it's clean:
Thread.new do
logger.debug("Spawned #{mod} process #{modpid}")
end

An interesting discussion about that: http://www.mikeperham.com/2013/02/23/signal-handling-with-ruby/

[bzizou]

We have to re-code completely the signal handling of the modules almighty and judas to implement "deferred signal handling".
A nice example may be found here: ddollar/foreman@5ab08c6