Disclaimer: I'm the CEO of jClarity who produces Censum.

For those who are looking to read the arcane output of a Java GC log, you can grab a 7-day free trial of Censum (https://www.jclarity.com/product/censum-free-trial/) - it parses GC logs (Java 6-9 all collectors) and gives you a host of analytics and graphs to help you figure out what's going on. We've also got blog posts on GC (https://www.jclarity.com/blog) and our slideshare http://www.slideshare.net/jclarity