Java was initially designed as a safe, managed environment. Nevertheless, Java HotSpot VM contains a “backdoor” that provides a number of low-level operations to manipulate memory and threads directly. This backdoor – sun.misc.Unsafe – is widely used by JDK itself in the packages like java.nio or java.util.concurrent. It is hard to imagine a Java developer who uses this backdoor in […]

This post is a second part of Ultimate Sets and Maps for Java. In the first part, we discussed memory-efficient implementations of sets and maps. These data structures efficiently support contains(key) operation. In this part of the article, we discuss more advanced querying: How to efficiently test that a collection of items meets a filtering criteria contains(key1) AND contains(key2) […]


Some time ago our team had been requested to develop several Java components for structured information retrieval. After the initial research, we concluded that standard approaches like inverted indexes are not well applicable to our problem because of specific business requirements. As a result we faced a necessity to design our own custom indexes and index processors […]