Forcing deallocation of large cache object in Java

Question

I use a large (millions) entries hashmap to cache values needed by an algorithm, the key is a combination of two objects as a long. Since it grows continuously (because keys in

Answer 1

Instead of using a HashMap or other map implementation as a cache you could try to use a framework specialized in caching. A well known caching framework for Java is Ehcache.

Caching frameworks let you usually configure expiration policies based on time (e.g. time to live, time to idle) or usage (e.g. least frequently used, least recently used), some may even allow you to specify a maximum amount of memory usage.