Does an Agent Impact Your App?

by February 13, 2018


Probably the most common consideration before deploying a monitoring agent into your application is “What is the agent footprint?”

A widely understood concept in physics is the observer effect whereby the simple act of observing a situation alters that situation.  In this case, the situation is your application and the observer is monitoring instrumentation such as a CA Application Performance Management (APM) agent.

The goal of most monitoring is to provide adequate visibility without sacrificing quality, meaning without significant impact to app performance nor end user experience. So why do most vendors shy away from definitive agent footprint claims? Well, the reality is, it depends.

Agent effect is dictated by several factors including your application architecture, platform, resource allocation, transaction load on the application and of course, the configuration of the monitoring.

Let’s take an example of two teams with Tomcat applications. The first app team may choose typical, default monitoring while the second team opts for maximum profiling. You might assume the second team should expect more impact from the monitoring.  It is certainly a possibility.  However, let’s say the response times for app B average 3 seconds. That means, even if the monitoring adds say 100ms, it would be undetectable to end users; only apparent in millisecond granularity measurements by a monitoring tool.  On the contrary, if app A was a very low latency app, averaging 100ms response times, introducing 50ms for monitoring would have a dramatic impact. Similar concepts apply for memory and CPU utilization impact.

In short, both the application and the agent play a role in determining the footprint. A simple round of testing can help app teams determine the level of visibility necessary for effective monitoring and triage as well as determine if any corresponding impact is truly detectable, worthwhile or lost in the noise. While CA APM agents default, typical settings work well for many applications, CA offers a significant advantage in that its agents are completely configurable. This means app teams have precision control over what is collected and the ability to fine tune the collection when monitoring an application more sensitive to change.


Take a look at this quick video to see more on this concept or get started with CA APM today by signing up for a free 30-day SaaS trial.