From: "Bartosz Dziewoński" <matma.rex@...>
Date: 2012-04-05T23:27:24+09:00
Subject: Re: Not a Memory Leak but Stale Objects - clears with GC.start

I don't know which gems are you using, but some gems interfacing with
external libraries may exhibit this behavior.

For example, RMagick has a tendency to eat up memory (on 1.8.x, and I
think on 1.9.x too), because it only "notifies" Ruby about the
interface objects, taking up a few kilobytes per image - but not
ImageMagick's image data, which can be huge. Since Ruby "thinks"
you're only using a little memory, it doesn't bother to fire up GC -
and in the meantime your script takes up a few gigs of RAM. (Calling
GC.start periodically is the recommended solution for this.)

-- Matma Rex