As discussed earlier, application performance is considered one of the most important milestones in any software application life cycle. It is also required that the application performs well consistently. This is one of the ways that we can ensure that application users will have the best experience with the application. It also means that the application is up and running well. An application performance monitoring tool tracks every request and response coming in and out of the application, processes information from the requests, and responds and displays in a graphical user interface. It means monitoring tools provide the administrators with the data necessary for quickly discovering, isolating, and solving problems impacting the performance.

The monitoring tools usually collect data about CPU utilization, memory requirements, bandwidth, and throughput. It is possible to have multiple monitoring systems for disparate monitoring. One of the important aspects of any application performance monitoring is to combine data from such monitoring systems into a statistical analysis engine and display it on a dashboard. The dashboard makes it easy to read the data logs for analysis. Application monitoring tools help administrators monitor application servers in order to comply with service level agreements (SLA). Business rules are set to send administrators an alert in the event of a problem. This ensures that business-critical features and applications are considered with higher priority. With the fast changing environments, it has become very important to have rapid deployments in production systems. Rapid deployments mean more chances to introduce errors impacting system architecture or to slow the system down.

Many implementations and tools are available based on these basic concepts. There is a huge and crowded market for application monitoring tools, including industry-leading and well-known tools like AppDynamics, New Relic, and Dynatrace. Apart from these known tools, there also exist open source application monitoring tools. The open source tools include Stagemonitor, Pinpoint, MoSKito, Glowroot, Kamon, and many more. We will look at each of these tools in detail in the following sections.