Backgroundrb Usage in Rails App

rubyonrails-talk
1

Hey Guys, '

I am developing a rails application for a client. Suffice it to say I have to do some long running tasks so of course I used my favorite plugin backgroundrb. Unfortunately I have a problem. I recently put some new work into a background task that requires the use of ruburple (a gem for connecting to IM protocols). Since then, I noticed that the worker that uses it sometimes just stops running with no explanation.

I checked the logs and I assume the relevant code is below:

libnm_glib_nm_state_cb: dbus returned an error.   (org.freedesktop.DBus.Error.ServiceUnknown) The name org.freedesktop.NetworkManager was not provided by any .service files

** (process:13909): CRITICAL **: xmlnode_set_attrib: assertion `value != NULL' failed

** (process:13909): CRITICAL **: xmlnode_set_attrib: assertion `value != NULL' failed

** (process:13909): CRITICAL **: xmlnode_set_attrib: assertion `value != NULL' failed #{my_rails_app}/releases/.../vendor/plugins/backgroundrb/framework/core.rb:149: [BUG] Segmentation fault ruby 1.8.6 (2007-06-07) [i486-linux]

My question is two-fold:

1) what's the best way to go about fixing this? How can I get more detailed information regarding the problem here. I assume the combination of the CRITICAL and the always fun segmentation fault is killing the thread. How can I find and eliminate the problem or implement exception handling so it ignores the issue.

2) How can I just force the thread back up if it dies. There has to be a way to have backgroundrb recreate the thread if it dies, right? I mean sure, that segmentation fault shouldn't happen but if it does, I need a way to bring the thread back online.

So if you could help with that I would appreciate it. I know ezra pokes around here every once in a while.

2

BTW the app is running on

ruby 1.8.6 (2007-06-07) [i486-linux] rails 2.0.1 ubuntu 7.10 gems are updated

and the weird part is that the "segmentation fault" doesn't happen every time. Most of the time it works just fine. However 1/5 times the fault will occur and the thread dies.

3

BTW, the line that it references for the segmentation fault:

backgroundrb/framework/core.rb:149

# method starts event loop in the process       def start_reactor         Signal.trap("TERM") { terminate_me }         Signal.trap("INT") { shutdown }         loop do           check_for_timer_events           user_thread_window #=> let user level threads run for a while           ready_fds = select(@read_ios,@write_ios,nil,0.005) # HERE IT FAILS!!!           #next if ready_fds.blank?

          next if !ready_fds or ready_fds.empty?

          ready_fds = ready_fds.flatten.compact           ready_fds.each do |t_sock|             if t_sock.is_a? UNIXSocket               handle_internal_messages(t_sock)             else               handle_external_messages(t_sock)             end           end         end       end

4

By any chance, can you run this thing with gdb? Also segmentation fault is one error from which process itself can't recover and must be restarted from outside. You can have a monit script for that.