In this article, Steven Haines talks about web application performance tuning which used to be more of an art than science. He proposes a method called wait-based tuning, making the entire process more measurable and, consequently, more scientific.
Read: A Formal Performance Tuning Methodology: Wait-Based Tuning
Steven explains why web application performance tuning is difficult to perform. A client request may go through several tiers suffering delays at different levels before a response is returned:
Input can come in the form of an HTML browser, a thick client, a mobile device, or a web service, which can pass through servlets running in one of a dozen different architectures or a portal container, that in turn may call enterprise beans, external web services, or delegate processing to a business rules engine. Each of these components may then interact with a content management system, a caching layer, a plethora of databases, and legacy systems.
The complexity of tuning today's web applications can be addressed by analyzing the architecture of the application and defining a series of wait-points marking the path traversed by a client request until it becomes a response that reaches back to the client. There are 2 types of wait-points, according to Steven:
- tier-based, marking the transition between tiers
- technology-based, mostly related to the usage of underneath infrastructure
Steven says that having "a set of wait-points identified, the tuning process is implemented by opening all tier-based wait-points and external dependency pools, generating balanced and representative load against the application, and tuning backwards, or tightening wait-points to maximize the performance of a request’s weakest link, but without saturating it."