Java G1 garbage collection in production

Question

Since Java 7 is going to use the new G1 garbage collection by default is Java going to be able to handle an order of magnitude larger heap without supposed \"devastating\" G

Answer 1

I have recently migrated part of Twicsy to a new server with 128GB RAM and decided to use 1.7. I started off using all the same memory settings as I used with 1.6 (I have several instances running doing various things, anywhere from 500mb of heap up to 15GB, and now a new one with 40GB) and that did not work out well at all. 1.7 seems to use more heap than 1.6, and I experienced a lot of issues over the first few days. I luckily had plenty of RAM to work with and bumped up the RAM for most of my processes, but still was having some issues. My normal MO was to use a very small minimum heap size of 16m, even with a max heap of several gigabytes, then turn on incremental GC. This kept the pauses at a minimum. That doesn't work now though, and I had to increase the minimum size to about what I expected to use on average in the heap, and that has worked out very well. I still have incremental GC turned on, but I will be trying it without. No pauses whatsoever now, and things seem to be running very fast. So, I think the moral of the story is don't expect your memory settings to translate perfectly from 1.6 to 1.7.