From: Alex Zunega <israels_son@...>
Date: 2009-09-03T12:43:11+09:00
Subject: Re: Threads - running something in background

7stud -- wrote:
> Alex Zunega wrote:
>> Hey guys,
>> 
>>  I've been studying Ruby for some weeks now but when it comes to
>> threads, I know that I am totally unskilled.
>> 
> 
> Also, you should realize that the @i in the class and the @i in the 
> thread are the same variable.
> Therefore, things like this can happen:
> 
> class Updater
>   attr_accessor :i
> 
>   def initialize
>     @i = 0
> 
>     Thread.new do
>       loop do
>         sleep(0.3)
>         @i += 1
>         puts "....#{@i}"
>       end
>     end
> 
>   end
> 
> end
> 
> 
> upd = Updater.new
> 
> 3.times do
>   sleep(2)
>   puts upd.i
> 
>   upd.i = 0    #<-----******
> end
> 
> --output:--
> ....1
> ....2
> ....3
> ....4
> ....5
> ....6
> 6
> ....1
> ....2
> ....3
> ....4
> ....5
> ....6
> ....7
> 7
> ....1
> ....2
> ....3
> ....4
> ....5
> ....6
> 6


Hey 7stud,

Thanks for the very prompt answer. I couldn't make myself clear and I'll 
try harder this time... :)

I've just removed two lines from the code you genially sent me. Removing 
these two lines I got the behavior I would like to have. See the code 
and results below:

>> class Updater
>>   attr_accessor :i
>> 
?>   def initialize
>>     @i = 0
>> 
?>     Thread.new do
?>       loop do
?>
?>         @i += 1
>> 
?>       end
>>     end
>> 
?>   end
>> 
?> end
=> nil
>> x.i
=> 213336
>> x.i
=> 237848
>> 

I just want something to time these iteration (one per second, for 
example), and everytime that I insert some "sleep" method, the Updater 
would "sum 1" to @i only when I try to access @i attribute.

What I expect, in other words, is to have an @i very close to the number 
of seconds of the object life, just to prove that it works...


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