[twic]

We run JVMs - running complex webapps on Tomcat - in production with 28 GB heaps. We don't have OOMs or chronic GC pauses. We don't reboot in between fortnightly releases.

We aren't running machines with 100 GB heaps, but i can tell you from personal experience that it's possible to exceed 8 GB without difficulty.

I doubt you'd have to look far to find people who were running with substantially bigger heaps on stock Sunacle/OpenJDK JVMs.

[kmasters]

I wont discredit your experience, however, I have been a consultant in several 64 bit shops, linux and solaris who had 64GB servers who could not scale above 8GB due to OOMs.

Also remember that if you are on linux doing that 28 GB heap you are living in the world of memory over-commit, which means if you actually tried to use that memory, you will probably segfault.

Again if you have done it great, no shop I have worked in, has been able to do it with app servers and keep their servers up reliably. Its a constant source of pain and I think JVM GC is not sufficient to scale at the level of current hardware.