His past contributions to the platform include character-stream readers and writers, reference objects, shutdown hooks, the NIO high-performance I/O APIs, library generification, and service loaders.

He was the lead engineer for the 1.2 and 5.0 releases, the specification lead for Java SE 6, and is currently leading the engineering team for the OpenJDK project. Mark holds a Ph.D. in Computer Science from the Massachusetts Institute of Technology.