Different locks for a singleton class

Question

I have a singleton class that contains 3 HashMap. Each hashmap acts like a pool. I put the unused entries in there. I encountered a concurrency modification exception so I was planning to implement synchronization on them. My problem is if I use the same lock for all of them, there would possibly be a performance issue. Because when I create an entry for that pool, it is through a web service call. Since I only need that each hashmap doesn't run concurrently, is it ok to create 3 object locks for them?

Answer 1

I recommend you to use ConcurrentHashMap .

The table is internally partitioned to try to permit the indicated number of concurrent updates without contention.

Try to tune performance with concurrencyLevel parameter.