Stack Exchange network consists of 183 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.
We trained 3.5M observations and 44 features using 64-bit R on an EC2 instance with 32GB ram and 4 cores. We used random forests and it worked well. Note that we had to preprocess/manipulate the data before training.