THE HOLY GRAIL: BUILDING APPLICATIONS THAT CAN SURVIVE THE UNPREDICTABLE WEB

摘要

We have all seen Web applications fail in spectacular ways under heavy load. This paper examines approaches that can be used to understand and eliminate this problem. Users are resigned to poor service when a web-site becomes overloaded and persist only when the alternatives are more painful (such as missing out on a ticket to see a much loved band in concert). If there is a choice, users will go to another web-site for the information or service. Once an application is deployed, the opportunities to fix the problem are often limited to a quick software change, or, more often than not, additional hardware. A better approach is to consider the issue during requirements (when sizing and SLA objectives are set) and application design (when architectural and user interface alternatives are still available). Spikes in usage are difficult to predict and it is a fact of life that resources are always limited. Developers must assume 'when' not 'if' there will be a problem and design accordingly.