JDK 5.0 is a huge step forward in developing concurrent Java classes and applications, providing concurrency building blocks for both novices and experts. This talk explores the new low-level concurrency utilities included in JDK 5.0, and examine their features and scalability.

Prior to the release of JDK 5.0, the Java platform provided basic primitives for writing concurrent programs, but they were just that – primitive – and difficult to use properly. In addition to many new high-level concurrency utilities, such as semaphores, mutexes, barriers, thread pools, and thread-safe collections, JDK 5.0 also includes a number of JVM-level enhancements for concurrency, and a set of low-level concurrency utilities for developing highly scalable, nonblocking concurrent algorithms in Java.

Even with built-in support for locking, it has not been practical to develop nonblocking concurrent algorithms in Java prior to JDK 5.0. With JVM support for accessing hardware-provided concurrency instructions (such as CAS) and the atomic variable classes provided in java.util.concurrent.atomic, it is now possible to develop highly scalable, wait-free, lock-free classes in Java.