title: ConcurrentHashMap vs HSQLDB in heavy traffic
body: <p>I am using ConcurrentHashMap as cache DB. Every 3 minutes I get objects from my real db and update ConcurrentHashMap values with new one. I have only 100 objects in map and user who came from web only read ConcurrentHashMap objects not insert or update. Let total system users is 4000/second,ConcurentHashMap still good way or should I change it with HSQLDB or any other in-memory cache DB.</p>