For an ideal amount of performance ,you can run a light-weight web framework with functions for managing logs on an in-memory database for monitoring and logging the traffic data , be it based on IP or User or Service called by user. The more important choice is the data storage you want to employ.
Best and most used free options are :
redis.io advanced key-value store
ehcache standards-based cache, actively developed, maintained and supported as a professional open source project by Terracotta
hazelcast an open source In-Memory Data Grid for faster execution and seamless elastic scalability
VoltDB an in-memory operational database