Interrupting Snapshots and the Java^{\mbox{\tiny TM}} Size() Method

Yehuda Afek, Nir Shavit, Moran Tzafrir

Abstract: The Java\(^{\mbox{\tiny TM}}\) developers kit requires a size() operation for all objects. Unfortunately, the best known solution, available in the Java concurrency package, has a blocking concurrent implementation that does not scale. This paper presents a highly scalable wait-free implementation of a concurrent size() operation based on a new lock-free interrupting snapshots algorithm for the classical atomic snapshot problem. This is perhaps the first example of the potential benefit from using atomic snapshots in real industrial code (the concurrency package is currently deployed on over 10 million desktops).