[Backgroundrb-devel] Cannot invoke ActiveRecord subclass accessors in DRb worker

dorian taylor dorian.taylor.lists at gmail.com
Thu Jun 15 16:04:25 EDT 2006

argh, forgot to add recipient.

---------- Forwarded message ----------
From: dorian taylor <dorian.taylor.lists at gmail.com>
Date: Jun 15, 2006 1:02 PM
Subject: Re: [Backgroundrb-devel] Cannot invoke ActiveRecord subclass
accessors in DRb worker
To: Ezra Zygmuntowicz <ezmobius at gmail.com>

On 6/15/06, Ezra Zygmuntowicz <ezmobius at gmail.com> wrote:
> Dorian-
>         Can you show me an example of your worker? You can shave it down to
> just the problem area. I will try to reproduce the problem and get
> back to you with an answer.

Sure, it's as simple as this:

class FoobarWorker
    include DRbUndumped

    def initialize(options={})
        @progress = 0
        @logger = BACKGROUNDRB_LOGGER

    def start_working(args={})
        Thread.new do
            @logger.debug "Trying to invoke stuff"
            person = Person.find(2)
            @logger.debug "First name is #{person.firstname}"


Or the new version:

class FoobarWorker2 < BackgrounDRb::Rails
  def do_work (args)
    @logger.debug("Attempting to get ActiveRecord instance")
    person = Person.find(2)
    @logger.debug("First name is #{person.firstname}")

In both cases, execution stops after (during?) the attempt to find()
the record. I set the ulimit and no core is being dumped. The Rails is
from trunk, and the database is MySQL 5.0 on a Debian/testing system.

>         But yeah threads can be hard to debug. But each worker does run in
> it's own thread and I have tested workers that use activerecord
> models by starting a bunch of them at once and they did not block and
> performed as they should. But I am interested to find any problems
> and fix them so please give a concrete example.

I'm sure you did test workers with ActiveRecord as I imagine it would
be a pretty common thing to want to do.

Perhaps it's something with the underlying software then? I'm not
sure. The ActiveRecord instances work fine if I invoke them directly
within a Thread in script/console.

Any insight would be great.



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