I know that needed to know more things about: user request, test with parameters, view logs, etc. to supply a 100% correct answer, but maybe someone has experience with a similar scenario. I will be happy with an aproximate answer as my start point...
For around 1500 concurrent users, with a normal average request to glassfish server:
1) What is the recommended hardware specification (memory, cores, etc)?
2) What Linux tuning is needed?
3) What configuration parameters for glassfish4 and JVM is need to set?
