From: cast_ent@... (Jeff)
Date: 2004-02-19T01:09:53+09:00
Subject: Weird GC behaviour or memory leak with NArray::to_na?

I have what appears to be a memory leak in my code, and I'm able to
reproduce it using the following test code:

require 'narray' 

a=Array.new(100,2)
200000.times{|x|
  #c=a.collect{|b| b+1} #This is OK. 
  #a.collect!{|b| b+1}  #This is OK.
  #a=a.collect{|b| b+1} #This is OK.
  #c=Array(a)           #This is OK.
  d=NArray.to_na(a)     #This results in huge memory bloat
}

Running this code shows my memory footprint increase monotonically
from ~2M to >20M... I killed the process at this point.  Any of the
other commented lines would run with a stable memory footprint.

However, if I add ObjectSpace::garbage_collect into the loop,
everything is fine.

Now to complicate matters further:  

require 'narray'
a=Array.new(100,2)
200000.times{|x|
  d=a.collect{|b| NArray.to_na([b,b])} #memory bloat despite explicit
GC!
  ObjectSpace::garbage_collect
}

This exhibits the growing memory footprint problem...... Help?  Note: 
I realize this example may be a little contrived, but my code does
this plus some more, requiring (IMHO) this approach.

Can someone explain this behaviour?  I use the .to_na constructor a
lot in my code, and really need to sort this out, otherwise I cannot
run my code for longer than brief periods before my system comes
crashing on down.

Thanks, Jeff