Here is a discussion about the source of the problem : http://stackoverflow.com/questions/30353272/garbage-collector-in-ruby-2-2-provokes-unexpected-cowtkalmus (Thomas Kalmus)
Calling the GC several times before forking the process solves the issue and I am quite surprised. I have also run the code using Ruby 2.0.0 and the issue doesn't even appear, so it must be related to this generational GC. However, if I...tkalmus (Thomas Kalmus)
How do I prevent the GC from provoking copy-on-write, when I fork my process ? I have recently been analyzing the garbage collector's behavior in Ruby, due to some memory issues that I encountered in my program (I run out of memory on m...tkalmus (Thomas Kalmus)
I have looked at the thing closely and it seems that the GC is not CoW friendly for sparse arrays. If I create an array of undefined size and populate it with random numbers in string format, the GC will launch the CoW in the fork. Howev...tkalmus (Thomas Kalmus)
This is without jemalloc. I made the changes just like requested, but the issue still persists. I get what I want, when I turn the GC off (GC.disabled), but this isn't an option since, anyway after a time my memory is filled with garbage.tkalmus (Thomas Kalmus)
Memory is duplicated when forking and calling GC in 2.2.1. The main issue here is that we are operating with huge data, going up to 3GB, and one fork is enough to kill our machine. We have written a small program that reproduces the...tkalmus (Thomas Kalmus)
tkalmus (Thomas Kalmus)06:29 AM Ruby Feature #11164: Garbage collector in Ruby 2.2 provokes unexpected CoW