Hi

I'm using the following:

$ md5sum freeroute.jar 
212b8886718d0a7b62b57c51362cdcf7  freeroute.jar

$ java -version
openjdk version "1.8.0_121"
OpenJDK Runtime Environment (build 1.8.0_121-b13)
OpenJDK 64-Bit Server VM (build 25.121-b13, mixed mode)

and I never had any crashes.
I'm running on a somewhat beefy headless server (i5-4690 CPU @ 3.50GHz, 8GB RAM) with ssh -X, which incidentally also runs a minecraft server at the same time

I always let Freeroute run until completion in one go (no saves or interrupts) which generally takes 40-50 optimize passes.

I'm not building really big (max euro card 100x160mm) but the boards are complicated enough (My project under development is currently 384 nodes, 86 nets on 100x80 with a mix of through-hole and SMD. routing takes about 2.5 hours.

Rienk