We are using a database (Apache Geode) that is written in Java. Our servers have 64g of RAM, so we set our Java heap (Xms and Xmx) at about 62g of RAM.
Most Java recommendations I've seen for situations like these is to use the CMS garbage collector, and to set the CMSInitiatingOccupancyFraction at somewhere around 68% (give or take a little, but not much).
But my question is: Why can't we set garbage collection to start at 95% instead of 68%? It seems maybe wasteful to run Java in such a fashion that you can never use more than 68% of your heap without causing non-stop Garbage Collections.
It's bugging us because we are at a stage where our database is doing non-stop garbage collections, and it's hard to justify more RAM when really the JVM has like 18 gigs free. :)
Thanks in advance for any advice.