Rails - Jul 2006 - ActiveRecord write stops script from responding to SIGTERM

We''ve got a small daemon we run on our servers, which looks something 
like this

require File.dirname(__FILE__) + ''/../config/boot''
require File.dirname(__FILE__) + ''/../config/environment''

ActiveRecord::Base.establish_connection

do
  m = Message.next_pending
  if m
    m.do_something
  else
    sleep 5
  end
end

Stuff gets place in this queue through other interactions with our web 
application and this guy processes them. This part all works fine.
The problem is when we try and stop the daemon running by sending a 
SIGTERM. If the daemon never found any message to process it exits fine, 
but if it did then it doesn not respond to the sigterm and we have to 
kill -9 it.

After a bit of investigation we found that our process would respond to 
SIGTERM properly as long as we had not done any ActiveRecord writes 
(reading from the database is fine). However as soon as we do an update 
or a create then the process stops responding to the SIGTERMs. It does 
however continue to run properly, and will find and process any new 
messages

This is running on an x86 linux machine (rails 1.1.2), anmd we''re using
mysql 4.1
I''m rather at a loss to explain this behaviour, anyone have any ideas

Thanks,

Fred

-- 
Posted via http://www.ruby-forum.com/.

Hi-

On Jul 4, 2006, at 2:28 AM, Frederick Cheung wrote:
> We''ve got a small daemon we run on our servers, which looks
something
> like this
>
> require File.dirname(__FILE__) + ''/../config/boot''
> require File.dirname(__FILE__) + ''/../config/environment''
>
> ActiveRecord::Base.establish_connection
>
> do
>   m = Message.next_pending
>   if m
>     m.do_something
>   else
>     sleep 5
>   end
> end
>
> Stuff gets place in this queue through other interactions with our web
> application and this guy processes them. This part all works fine.
> The problem is when we try and stop the daemon running by sending a
> SIGTERM. If the daemon never found any message to process it exits  
> fine,
> but if it did then it doesn not respond to the sigterm and we have to
> kill -9 it.
>
> After a bit of investigation we found that our process would  
> respond to
> SIGTERM properly as long as we had not done any ActiveRecord writes
> (reading from the database is fine). However as soon as we do an  
> update
> or a create then the process stops responding to the SIGTERMs. It does
> however continue to run properly, and will find and process any new
> messages
>
> This is running on an x86 linux machine (rails 1.1.2), anmd we''re
> using
> mysql 4.1
> I''m rather at a loss to explain this behaviour, anyone have any
ideas
>
> Thanks,
>
> Fred

Fred-

	I''m not entirely sure why your daemon stops responding after a db  
write. But you could convert your daemon over to use my BackgrounDRb  
plugin[1] which was written for situations exactly like what you are  
doing here.

Check it out here:

*Home page: http://backgroundrb.rubyforge.org
*svn repo: svn://rubyforge.org//var/svn/backgroundrb
*Mailing list: http://rubyforge.org/mailman/listinfo/backgroundrb-devel


-Ezra
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://wrath.rubyonrails.org/pipermail/rails/attachments/20060704/93d57ee7/attachment-0001.html