[hierro]

I have to disagree with that. We've been using graphicsmagick via cgo on memecrunch.com (alexa 30K, 8K in US) for 9 months and we're serving around 500K images per day on a single server without any issues. In fact, I've just logged in and the app is currently using 0.3% of the memory (out of 64GB) after running for a couple of weeks, since the last update I pushed to production. I don't believe graphicsmagick leaks memory in any significant way.

Of course, you need to cache the thumbnails for a reasonable time once they're generated, otherwise the CPU usage will skyrocket, but that's pretty easy to achieve with nginx's proxy_cache directive.