Ferret talk - Nov 2007 - Reducing dependency on remote ferret process

Hi.

We use FerretDrb for search. If the ferret process is down, our entire 
application comes down the moment we try to save a model which is indexed.

Is there a way to decouple this relationship such that we can somehow 
resume normal operations despite ferret being down and not index the model?

Thanks.

Morten

Morten wrote:
> Hi.
> 
> We use FerretDrb for search. If the ferret process is down, our entire 
> application comes down the moment we try to save a model which is indexed.
> 
> Is there a way to decouple this relationship such that we can somehow 
> resume normal operations despite ferret being down and not index the model?
> 
> Thanks.
> 
> Morten
I really don''t understand your concern. I could also say "if the
web
server process is down, our entire application is down" (assuming
you''re
talking about a web app). The FerretDrb process shouldn''t be down. If 
you continue even if it''s down, your index will become out of date. 
Depending on your data that may or may not be worse than crashing.

Hongli Lai wrote:
> Morten wrote:
>> Hi.
>>
>> We use FerretDrb for search. If the ferret process is down, our entire 
>> application comes down the moment we try to save a model which is
indexed.
>>
>> Is there a way to decouple this relationship such that we can somehow 
>> resume normal operations despite ferret being down and not index the
model?
>>
>> Thanks.
>>
>> Morten
> 
> I really don''t understand your concern. I could also say "if
the web
> server process is down, our entire application is down" (assuming
you''re
> talking about a web app). The FerretDrb process shouldn''t be down.
If
> you continue even if it''s down, your index will become out of
date.
> Depending on your data that may or may not be worse than crashing.
I don''t think your comparison is quite fair. Ferret is nice, but
it''s
not fully matured compared to Apache, MySQL and so on. At least I''m 
having more stability issues with it than I''ve had with the other 
processes that I base my work on, which is why I think my concern is 
completely valid.

Br,

Morten

Hey ..

unfortunately, no .. not with the current construction.
However, there might be a chance to switch to a
messaging service like ap4r, so your indexing
requests doesn''t get lost.

I think there are some considerations about re-factoring
the drb server, so maybe this dependency might be
dropped in the future..

Cheers
  Ben



On 2007-11-11, at 16:09, Morten wrote:
>
> Hi.
>
> We use FerretDrb for search. If the ferret process is down, our entire
> application comes down the moment we try to save a model which is  
> indexed.
>
> Is there a way to decouple this relationship such that we can somehow
> resume normal operations despite ferret being down and not index the  
> model?
>
> Thanks.
>
> Morten
>
>
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
Gruss
  Ben
---
Benjamin Krause
http://www.omdb.org/
bk at benjaminkrause.com

Rails-Schulung "Advancing with Rails" mit David A. Black
19.11.-22.11.2007, Berlin-Mitte
Details u. Anmeldung: http://www.railsschulung.de


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Let me take a wild guess on this one.

On ACTS_AS_FERRET_GEM_ROOT/lib/index.rb

def ferret_create
  if ferret_enabled?
    logger.debug "ferret_create/update: #{self.class.name} :
#{self.id}"
    self.class.aaf_index << self
  else
    ferret_enable if @ferret_disabled == :once
  end
    true # signal success to AR
end

Try wrapping "aaf_index<<" like this

begin
  self.class.aaf_index << self
rescue Exception => e
  logger.warn "Error creating/updating document:
#{e.inspect}\n#{e.backtrace.join("\n\t")}"
end

Mind I''m just reading the source and writing the code here straight
away. In the event of my theory being right, this would gracefully
handle exceptions related to adding an entry to the index by dropping
a warning in the AAF log file and moving on.

I think this could be an optional in config/initializers (Rails 2.0)
perhaps, as in

config.aaf.exception_on_save = true

IMHO, of course.


On Nov 12, 2007 8:36 AM, Benjamin Krause <bk at benjaminkrause.com>
wrote:
> Hey ..
>
> unfortunately, no .. not with the current construction.
> However, there might be a chance to switch to a
> messaging service like ap4r, so your indexing
> requests doesn''t get lost.
>
> I think there are some considerations about re-factoring
> the drb server, so maybe this dependency might be
> dropped in the future..
>
> Cheers
>  Ben
>
>
>
>
>
>
> On 2007-11-11, at 16:09, Morten wrote:
>
> Hi.
>
> We use FerretDrb for search. If the ferret process is down, our entire
> application comes down the moment we try to save a model which is indexed.
>
> Is there a way to decouple this relationship such that we can somehow
> resume normal operations despite ferret being down and not index the model?
>
> Thanks.
>
> Morten
>
>
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
>
>
>
> Gruss
>  Ben
> ---
> Benjamin Krause
> http://www.omdb.org/
> bk at benjaminkrause.com
>
> Rails-Schulung "Advancing with Rails" mit David A. Black
> 19.11.-22.11.2007, Berlin-Mitte
> Details u. Anmeldung: http://www.railsschulung.de
>
>
>
> _______________________________________________
> Ferret-talk mailing list
> Ferret-talk at rubyforge.org
> http://rubyforge.org/mailman/listinfo/ferret-talk
>

Morten,

If you''re still looking at how to solve this, here is what I did.   
This is just a hack, but I didn''t really have a choice, this coupling  
was killing my entire application stack.

--- act_methods.rb      (revision 1534)
+++ act_methods.rb      (working copy)
@@ -185,9 +185,10 @@
        end
        logger.info "default field list: #{aaf_configuration[:ferret] 
[:default_field].inspect}"

-      if options[:remote]
-        aaf_index.ensure_index_exists
-      end
+      # FIXME fix and send a patch to the AAF team
+      # if options[:remote]
+      #   aaf_index.ensure_index_exists
+      # end
      end

-- 
Peter Jones - 303-669-2637
pmade inc.  - http://pmade.com

On Nov 11, 2007, at 08:09, Morten wrote:
> We use FerretDrb for search. If the ferret process is down, our entire
> application comes down the moment we try to save a model which is  
> indexed.
>
> Is there a way to decouple this relationship such that we can somehow
> resume normal operations despite ferret being down and not index the  
> model?

I''ve added suggestions from Julio Cesar Ody and Peter Jones to the  
relevant ticket:

http://projects.jkraemer.net/acts_as_ferret/ticket/149

If anyone has another solution, consider adding it to the ticket.  
Quote code in trac like this:

{{{

my code

}}}