Tigris: A Java-based Cluster I/O System

We present Tigris, a high-performance computation and I/O substrate for clusters of workstations, implemented entirely in Java. Tigris automatically balances resource load across the cluster as a whole, shielding applications from asymmetries in CPU, I/O, and network performance. This is accomplished through the use of a data ow programming model coupled with a workbalancing distributued queue. To meet the performance challenges of implementing such a system in Java, we present Jaguar, a system which enables direct, protected access to hardware resources (such as fast network interfaces and disk I/O) from Java. Jaguar yields an orderof-magnitude performance boost over the Java Native Interface for Java bindings to system resources. We demonstrate the applicability of Tigris through TigrisSort, a one-pass, parallel, disk-to-disk sort exhibiting