Rails - Jul 2007 - backgroundrb concurrent client access, results services

First thank to backgroundrb, it sure makes distribute computing a lot
easier.  A couple of questions:
1. I don''t fully understand the reason for Results services, can I just
create instance vars, methods within the Worker class help to exposed
shared result data?  I did notice about results being alive after the
Worker is deleted. Is this the only reason?

2. Continue with the first question, since I have no need to access data
after the Worker is deleted, I rather not introduce additional book
keeping. I want to introduce instance vars and methods to access data
within the Worker. Will I have to worry data corruption/sync problem if
I have multiple MiddleMan clients  accessing the same Worker that may be
calling instance vars and/or methods at the same time. Or if I just use
the Results service, my worries goes away. I guess I will spend sometime
soon digging into the codes to better understand it, but in the mean
time any info would be greatly appreciated.

Thanks,
Mike

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On Jul 14, 2007, at 3:37 PM, Mike Hang wrote:
>
> First thank to backgroundrb, it sure makes distribute computing a lot
> easier.  A couple of questions:
> 1. I don''t fully understand the reason for Results services, can I
> just
> create instance vars, methods within the Worker class help to exposed
> shared result data?  I did notice about results being alive after the
> Worker is deleted. Is this the only reason?
>
> 2. Continue with the first question, since I have no need to access  
> data
> after the Worker is deleted, I rather not introduce additional book
> keeping. I want to introduce instance vars and methods to access data
> within the Worker. Will I have to worry data corruption/sync  
> problem if
> I have multiple MiddleMan clients  accessing the same Worker that  
> may be
> calling instance vars and/or methods at the same time. Or if I just  
> use
> the Results service, my worries goes away. I guess I will spend  
> sometime
> soon digging into the codes to better understand it, but in the mean
> time any info would be greatly appreciated.
>
> Thanks,
> Mike
Mike-

	Stay away from the results worker and just use methods and instance  
variables. The results worker is only useful if you want to keep some  
results around after you kill your worker. ALso the results worker is  
a tad broken right now as well.

	If you need to have multiple access to variables in a worker then  
you may need to synchronize access to instance variables and methods  
with a mutex. add a ''lock'' helper method like this to your
worker:

def lock
   @_lock ||= Mutex.new
   @_lock.synchronize { yield }
end

	And then use it every time you have an area of code that could get  
accessed by multiple clients at once:

def important_method
   lock do
     # some important thing in here that only
     #should be accessed by one thread at a time
   end
end


Cheers-
-- Ezra Zygmuntowicz 
-- Founder & Ruby Hacker
-- ez-NLltGlunAUd/unjJdyJNww@public.gmane.org
-- Engine Yard, Serious Rails Hosting
-- (866) 518-YARD (9273)



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