[julia-users] Release memory GC

[Thuener Silva]

I have a code that uses a lot of memory and I'm trying to release some of 
it but without success. I made up an examples to illustrate the problem:

function memuse()
  return string(round(Int,parse(Int,readall(`ps -p 29563 -o 
rss=`))/1024),"M")
end

function test()
  for i = 1:2
   println("\ni=$i")
   a = rand(10000,10000)
   println("Created a $(memuse())")
   a = 0
   gc()
   println("Release a $(memuse())\n")

   b = rand(10000,10000)
   println("Created b $(memuse())")
   b = 0
   gc()
   println("Release b $(memuse())\n")
   
   c = rand(10000,10000)
   println("Created c $(memuse())")
   c =0
   gc()
   println("Release c $(memuse())\n")
  end
end

test()


Output:

i=1
Created a 918M
Release a 918M

Created b 1681M
Release b 1681M

Created c 2444M
Release c 2444M


i=2
Created a 3207M
Release a 2444M

Created b 3207M
Release b 2444M

Created c 3207M
Release c 2444M




This code only needs 918M to run but uses 3207M.

Questions:
Why gc() is not releasing unused memory? 
There is some way to force garbage collector to release? 
Why garbage collector releases some memory only on the second iteration?


Thanks,
Thuener