[Backgroundrb-devel] Problems running backgroundrb

hemant kumar gethemant at gmail.com
Wed Feb 13 09:42:47 EST 2008


On Wed, 2008-02-13 at 09:20 -0500, John Wells wrote:
> On Feb 12, 2008 9:03 PM, hemant <gethemant at gmail.com> wrote:
> > On Tue, Feb 12, 2008 at 12:05 AM, John Wells
> >
> > <lists at sourceillustrated.com> wrote:
> > >
> > > On Feb 11, 2008 1:28 PM, hemant <gethemant at gmail.com> wrote:
> > >  > On Mon, Feb 11, 2008 at 8:20 PM, John Wells <lists at sourceillustrated.com> wrote:
> > >  > > On Feb 11, 2008 5:03 AM, hemant kumar <gethemant at gmail.com> wrote:
> > >  > >  >
> > >  > >  > On Mon, 2008-02-11 at 00:55 -0800, Alex Soto wrote:
> > >  > >  > > does require 'lib/formatters' work?
> > >  > >  > >
> > >  > >  > >
> > >  > >  > > On Feb 10, 2008, at 10:11 PM, John Wells wrote:
> > >  > >  > >
> > >  > >  > > > Hi guys,
> > >  > >  > > >
> > >  > >  > > > New to backgroundrb, and I like it very much conceptually, but I'm
> > >  > >  > > > struggling to get it to run successfully. I started with trunk, but
> > >  > >  > > > was getting a very strange gem require error when starting a worker
> > >  > >  > > > (though it wasn't telling me which gem was missing)....see here:
> > >  > >  > > > http://pastie.caboo.se/150225
> > >  > >  >
> > >  > >  > Its not complaining about any missing gems, rather its not able to load
> > >  > >  > workers defined inside lib/workers directory. You must define at least
> > >  > >  > one worker, before you can start bdrb. In case, you have already defined
> > >  > >  > a worker, Can we have a look at the code of your worker?
> > >  > >
> > >  > >  Thanks for your help. Sure thing...the code is below. However, I'm
> > >  > >  very curious...how did you determine this was the problem? Just so I
> > >  > >  know what to look for in the future.
> > >  >
> > >  > Because, when I saw error at:
> > >  >
> > >  > http://pastie.caboo.se/150225
> > >  >
> > >  > It clearly says thats start_worker is failing on 114 line. Generally
> > >  > this happens, when bdrb is not able to load a particular worker file.
> > >  > Also, you see empty string "gem_original_require': no such file to
> > >  > load --  (LoadError)" because bdrb is not able to get name of worker
> > >  > file to load correctly.
> > >  >
> > >  >
> > >  >
> > >  > >
> > >  > >  ===== controller that instantiates worker =====
> > >  > >  class Admin::BatchController < Admin::ApplicationController
> > >  > >
> > >  > >   def initialize
> > >  > >     super
> > >  > >     @formats = GW::BatchListing::ListingRow.formats
> > >  > >     @part_of = :admin
> > >  > >   end
> > >  > >
> > >  > >   def get_progress
> > >  > >     if request.xhr?
> > >  > >       progress_percent = MiddleMan.get_worker(session[:job_key]).progress
> > >  > >       render :update do |page|
> > >  > >         page.call('progressPercent', 'progressbar', progress_percent)
> > >  > >         page.redirect_to( :action => 'done')   if progress_percent >= 100
> > >  > >       end
> > >  > >     else
> > >  > >       redirect_to :action => 'index'
> > >  > >     end
> > >  > >   end
> > >  > >
> > >  > >   def done
> > >  > >     errors = "DONE " + MiddleMan.get_worker(session[:job_key]).errors
> > >  > >     if errors.size > 0
> > >  > >       flash[:notice] = errors.join("<br/>")
> > >  > >     else
> > >  > >       flash[:notice] = "Successful load."
> > >  > >     end
> > >  > >     MiddleMan.delete_worker(session[:job_key])
> > >  > >   end
> > >  > >
> > >  > >   def add
> > >  > >     @user = User.find(params[:id])
> > >  > >     @cats = Category.find(:all, :conditions=>"parent_id is null")
> > >  > >     if request.post?
> > >  > >       listings = params[:listings]
> > >  > >       content_type = listings.content_type.chomp
> > >  > >       if "application/zip"!=content_type and
> > >  > >          "application/x-zip-compressed"!=content_type
> > >  > >         flash[:notice] =
> > >  > >           "Only files of type application/zip " +
> > >  > >           "and application/x-zip-compressed " +
> > >  > >           "can be used. You uploaded #{content_type}."
> > >  > >       else
> > >  > >         # write out to tmp file
> > >  > >         tmpfile = "/tmp/#{rand 500000}.zip"
> > >  > >         open(tmpfile, "w") do |f|
> > >  > >           f << listings.read
> > >  > >         end
> > >  > >         parser =
> > >  > >           GW::BatchListing::ListingParser.new(params[:format],
> > >  > >                                                         params[:listing_type],
> > >  > >                                                         @user)
> > >  > >         session[:job_key] =
> > >  > >             MiddleMan.new_worker(:class => :foo_worker,
> > >  > >                                  :args => parser)
> > >  > >       end
> > >  > >     end
> > >  > >   end
> > >  > >  end
> > >  > >
> > >  >
> > >  > There are couple of problems with above code, for example,
> > >  > MiddleMan.get_worker is not defined. To get an idea about, which
> > >  > methods are defined for MiddleMan, have a look at,
> > >  >
> > >  > http://backgroundrb.rubyforge.org/classes/BackgrounDRb/WorkerProxy.html
> > >  >
> > >  > Also, you should read README file that comes with plugin.
> > >  >
> > >  > >  ===== and the worker itself =====
> > >  > >  class BatchImportWorker < BackgrounDRb::MetaWorker
> > >  > >   attr_reader :progress
> > >  > >   attr_reader :errors
> > >  > >   set_worker_name :batch_import_worker
> > >  > >
> > >  > >   def create(args = nil)
> > >  > >     # this method is called, when worker is loaded for the first time
> > >  > >   end
> > >  > >
> > >  > >   def do_work(parser)
> > >  > >     @progress = 0
> > >  > >     @errors = parser.process(tmpfile)
> > >  > >   end
> > >  > >  end
> > >  >
> > >  > Well, I find  no problems with above worker code, and it should load.
> > >  > Create a fresh rails app and see if bdrb works there.
> > >
> > >
> > > Ok, sorry... I was working from the old InfoQ article by Ezra and the
> > >  api docs. I probably made some bad assumptions there...I will take a
> > >  hard look and try it again.
> > >
> > >  Thanks for your help!
> >
> > Just catching up on this. So, did you manage to get it work after
> > reading latest docs?
> > If yes, can you tell us, why bdrb was not able to load your worker?
> >
> 
> It was a number of small little errors, and some big ones. Perhaps the
> most damning was:
> 
> @errors = parser.process(tmpfile)
> 
> You'll note tmpfile doesn't exist in this context ;) That would cause a problem.
> 
> I have my solution working  now and it's working well. I really
> appreciate your help.
> 
> My biggest hurdle with backgroundrb was the fact that I have some very
> complicated business rules taking place on the brdb side of things,
> and without an easy way to step through these with a debugger, lots of
> things can go wrong and it makes life more difficult. Running
> script/backgroundrb without arguments and using puts and inspect
> helps, but hooking to it with a debugger so that one could inspect
> variables, etc would be extremely useful. I started going down the
> path of getting NetBeans' debugger to work with it, but quickly
> realized it was going to take more time than I had given my current
> project.

I have similar project, where I have complicated set of business rules
in workers. Stepping through debugger is no solution, Please write test
cases for workers, thats the only way.



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