Ruby on Rails

> On Sat, Mar 23, 2013 at 5:37 PM, tamouse mailing lists
> <tamouse.lists@gmail.com> wrote:
>>
>> On Sat, Mar 23, 2013 at 1:20 PM, Jodi Showers <jodi@homestars.com> wrote:
>> > I'm just about to scale to a second app server - so good timing
>> >
>> > in which ways did you find cron to be a poor choice ? on a single server
>> > they meet our needs nicely
>> >
>> > you'd only run one clock instance per cluster - so much like cron (ie.
>> > no
>> > interserver clock scheduling). Have you tried using clock driven from a
>> > schedule described in the db (like a centralized cron, useful for
>> > failover)
>> > ?
>> >
>> > Any thoughts you have on this topic appreciated
>> >
>> > As for the OP, I hope they can see the short and long term options
>> > before
>> > them.
>> >
>> > J
>> >
>> >
>> >
>> >
>> > On Sat, Mar 23, 2013 at 2:01 PM, tamouse mailing lists
>> > <tamouse.lists@gmail.com> wrote:
>> >>
>> >> Please bottom post (appending). It makes responses easier to find.
>> >>
>> >> On Sat, Mar 23, 2013 at 10:32 AM, Jodi Showers <jodi@homestars.com>
>> >> wrote:
>> >> > that is a good thinking, just like normalization - then comes a time
>> >> > to
>> >> > denormalize
>> >> >
>> >> > we have millions of visitors per month - and about 50 asynch
>> >> > processes -
>> >> > having one rails process deal with all those asynchs rather than one
>> >> > per
>> >> > is
>> >> > not helpful in any way
>> >> >
>> >> > using a best practice such as my approach is not harder to implement
>> >> > and
>> >> > will scale - choosing an approach of equal complexity that won't
>> >> > scale
>> >> > doesn't hold water
>> >> >
>> >> >
>> >> > On Sat, Mar 23, 2013 at 11:27 AM, Colin Law <clanlaw@googlemail.com>
>> >> > wrote:
>> >> >>
>> >> >> On 23 March 2013 15:15, Jodi Showers <jodi@homestars.com> wrote:
>> >> >> > for regularly scheduled jobs, I use a mixture of cron (to create a
>> >> >> > delayed
>> >> >> > job), and the delayed_job itself
>> >> >> >
>> >> >> > the crontab instance is very light, just a small (non-rails) rb
>> >> >> > script
>> >> >> > to
>> >> >> > insert the delayed_job in the delayed_jobs table
>> >> >> >
>> >> >> > then the delayed_job instance will pickup the job and run it
>> >> >> >
>> >> >> > in your instance, I would create a class method on the Test model
>> >> >> > -
>> >> >> > something like
>> >> >> >
>> >> >> > def self.remove_old_unpublished
>> >> >> > delete_all(["created_at < ? and state in('unpublished')",
>> >> >> > 24.hours.ago])
>> >> >> > end
>> >> >> >
>> >> >> > cron entry like this:
>> >> >> > 05 1 * * * cd /path/to/current && RAILS_ENV=production
>> >> >> > /path/to/current/lib/delayed_job_cron_jobs/create_delayed_job.rb
>> >> >> > --model
>> >> >> > "Test" --method "remove_old_unpublished" --queue "general"
>> >> >> > --arguments
>> >> >> > "{:any_argument => 42}"
>> >> >> >
>> >> >> > the following gist is a script to insert delayed_jobs from cron
>> >> >> > https://gist.github.com/jshow/5228049
>> >> >> >
>> >> >> > fyi, the reason to take this route over the simpler rake route
>> >> >> > (run
>> >> >> > rake
>> >> >> > task from cron) is performance and memory usage - this method will
>> >> >> > save
>> >> >> > you
>> >> >> > a bunch of both.
>> >> >>
>> >> >> I am always suspicious of the idea of doing something in a more
>> >> >> complex way in order to save resources. It is only worth spending
>> >> >> the
>> >> >> additional time developing the solution if computing resources are
>> >> >> likely to be an issue. Computing resources are usually cheaper than
>> >> >> human resources.
>> >> >>
>> >> >> Colin
>> >> >>
>> >> >> --
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>> >> >>
>> >> >
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>> >> >
>> >>
>> >> If you're working in a distributed, multi-server and multi-process
>> >> environment, cron is a poor solution. DelayedJobs and several others
>> >> work in a distributed environment much better. I have been using the
>> >> gem clockwork in addition to DJ, which makes things very simple.
>> >>
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>> >>
>> >
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>> >
>>
>> The primary issue when you bring in multiple servers is
>> synchronization of the workers. Cron can't do that, as it only knows
>> about one server. Having something that workers can distribute over
>> requires something more sophisticated. That's what DJ is really about.
>> Using clockwork makes it all the easier coming from cron.
>>
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>
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>

This is a bottom post. Please follow suit.

On Sat, Mar 23, 2013 at 4:47 PM, Jodi Showers <jodi@homestars.com> wrote:
> yes - I know - I use DJ presently
>
> my question was about what advantages you see with clockwork over cron -
> other than syntax I don't see any advantages

The advantage is that you'd need to be running cron on each of your
servers managing workers, whereas clockwork only needs to run on one
to keep things synchronized.

> now if the schedule was stored in the db, and I could run multiple
> clockworks on each server there would some inherent scheduling failover (DJ
> already provides job/worker failover)

If you do decide to go that route, DJ can handle the requeuing itself,
not needing anything else. It's just a bit more configuration and
such.

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