|
USITS '03 Abstract
Conflict-Aware Scheduling for Dynamic Content Applications
Cristiana Amza, Alan L. Cox, Rice University; Willy Zwaenepoel, EPFL
Abstract
We present a new lazy replication technique, suitable for scaling the back-end database of a dynamic content site using a cluster of commodity computers. Our technique, called conflict-aware scheduling, provides both throughput scaling and 1-copy serializability. It has generally been believed that this combination is hard to achieve through replication because of the growth of the number of conflicts. We take advantage of the presence in a database cluster of a scheduler through which all incoming requests pass. We require that transactions specify the tables that they access at the beginning of the transaction. Using that information, a conflict-aware scheduler relies on a sequence-numbering scheme to implement 1-copy serializability, and directs incoming queries in such a way that the number of conflicts is reduced.
We evaluate conflict-aware scheduling using the TPC-W e-commerce benchmark. For small clusters of up to eight database replicas, our evaluation is performed through measurements of a web site implementing the TPC-W specification. We use simulation to extend our measurement results to larger clusters, faster database engines, and lower conflict rates.
Our results show that conflict-awareness brings considerable benefits compared to both eager and conflict-oblivious lazy replication for a large range of cluster sizes, database speeds, and conflict rates. Conflict-aware scheduling provides near-linear throughput scaling up to a large number of database replicas for the browsing and shopping workloads of TPC-W. For the write-heavy ordering workload, throughput scales, but only to a smaller number of replicas.
- View the full text of this paper in HTML or PDF.
Until March 2004, you will need your USENIX membership identification in order to access the full papers. The Proceedings are published as a collective work, © 2003 by the USENIX Association. All Rights Reserved. Rights to individual papers remain with the author or the author's employer. Permission is granted for the noncommercial reproduction of the complete work for educational or research purposes. USENIX acknowledges all trademarks within this paper.
- If you need the latest Adobe Acrobat Reader, you can download it from Adobe's site.
|
Need help? Use our Contacts page.
