Running ES 1.5.2 and Windows 2008 R2 Ent
1 of my nodes became unresponsive. So I logged only to see 100% memory usage on the Windows server. I stopped the ES process and the memory got completely freed up. I checked the logs there's no OOM exceptions also there's no dump files (Sometimes with a crash you get the dump file).
The only error that shows up is a index throttling error though that only started hapening 2-3 hours into the bulking process. So bulking had started ok for a couple of hours and then started throttling.
So I can't explain the 100% usage.