From: "ara.t.howard" <ara.t.howard@...>
Date: 2007-07-20T11:45:43+09:00
Subject: Re: Array flatten memory "leak"?


On Jul 19, 2007, at 4:07 PM, Ron M wrote:

> ###################################################################### 
> ###
> #  This unexpectedly grows to 200+MB.
          not
> ###################################################################### 
> ###
> a = (1..200000).map{|x| [x.to_s]};a.length
> b = a.flatten.map{|x| x.to_i} ; b.length

a         #=> big array
a.flatten #=> copy of said big array
a.flatten #=> copy of flattened array

so you take two copies to get one and neglect to call GC.start

> puts `grep VmSize /proc/#{$$}/status`           ######## under 20 MB
> (1..100).each{|x| b.pack("I*").unpack("I*");}
> puts `grep VmSize /proc/#{$$}/status`           ######## WHOA GREW  
> TO 1/4 GB.
>
>
> ###################################################################### 
> ###
> #  This stays at 20MB
> ###################################################################### 
> ###
> a = (1..200000).map{|x| [x.to_s]};a.length
> b = a.map{|x| x[0].to_i} ; b.length
> puts `grep VmSize /proc/#{$$}/status`         ######## under 20 MB
> (1..100).each{|x| b.pack("I*").unpack("I*");}
> puts `grep VmSize /proc/#{$$}/status`         ######## still 20 MB
>

a @ http://drawohara.com/
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