Application Performance Management, or APM, is the monitoring and management of the availability and performance of software applications. Different people can interpret this definition differently so this article attempts to qualify what APM is, what it includes, and why it is important to your business. If you are going to take control of the performance of your applications, then it is important that you understand what you want to measure and how you want to interpret it in the context of your business.
As applications have evolved from stand-alone applications to client-server applications to distributed applications and ultimately to cloud-based elastic applications, application performance management has evolved to follow suit. When we refer to APM we refer to managing the performance of applications such that we can determine when they are behaving normally and when they are behaving abnormally. Furthermore, when someone goes wrong and an application is behaving abnormally, we need to identify the root cause of the problem quickly so that we can remedy it.
We might observe things like:
Once we have captured performance metrics from all of these sources, we need to interpret and correlate them with respect to the impact on your business transactions. This is where the magic of APM really kicks in. APM vendors employ experts in different technologies so that they can understand, at a deep level, what performance metrics mean in each individual system and then aggregate those metrics into a holistic view of your application.
The next step is to analyze this holistic view your application performance against what constitutes normalcy. For example, if key business transactions typically respond in less than 4 seconds on Friday mornings at 9am but they are responding in 8 seconds on this particular Friday morning at 9am then the question is why? An APM solution needs to identify the paths through your application for those business transactions, including external dependencies and environmental infrastructure, to determine where they are deviating from normal. It then needs to bundle all of that information together into a digestible format and alert you to the problem. You can then view that information, identify the root cause of the performance anomaly, and respond accordingly.
It probably seems obvious to you that APM is important, but you will likely need to answer the question of APM importance to someone like your boss or the company CFO that wants to know why she must pay for it. In order to qualify the importance of APM, letís consider the alternatives to adopting an APM solution and assess the impact in terms of resolution effort and elapsed down time.
First letís consider how we detect problems. An APM solution alerts you to the abnormal application behavior, but if you donít have an APM solution then you have a few options:
A synthetic transaction is a transaction that you execute against your application and with which you measure performance. Depending on the complexity of your application, it is not difficult to build a small program that calls a service and validates the response. But what do you do with that program? If it runs on your machine then what happens when youíre out of the office? Furthermore, if you do detect a functional or performance issue, what do you do with that information? Do you connect to an email server and send alerts? How do you know if this is a real problem or a normal slowdown for your application at this hour and day of the week? Finally, detecting the problem is one thing, how do you find the root cause of the problem?
The next option is manually instrumenting your application, which means that you add performance monitoring code directly to your application and record it somewhere like a database or a file system. Some challenges in manual instrumentation include: what parts of my code do I instrument, how do I analyze it, how do I determine normalcy, how do I propagate those problems up to someone to analyze, what contextual information is important, and so forth. Plus you have introduced a new problem: you have introduced performance monitoring code into your application that you need to maintain. Furthermore, can you dynamically turn it on and off so that your performance monitoring code does not negatively affect the performance of your application? If you learn more about your application and identify additional metrics you want to capture, do you need to rebuild your application and redeploy it to production? What if your performance monitoring code has bugs?
There are other technical options, but what I find most often is that companies are alerted to performance problems when their custom service organization receives complaints from users. I donít think I need to go into details about why this is a bad idea!
Next letís consider how we identify the root cause of a performance problem without an APM solution. Most often I have seen companies do one of two things:
Log files are great sources of information and many times they can identify functional defects in your application (by capturing exception stack traces), but when experiencing performance issues that do not raise exceptions, they typically only introduce additional confusion. You may have heard of, or been directly involved in, a production war room. These war rooms are characterized by finger pointing and attempts to indemnify oneís own components so that the pressure to resolve the issue falls on someone else. The bottom line is that these meetings are not fun and not productive.
Alternatively, and usually in parallel, the development team is tasked with reproducing the problem in a test environment. The challenge here is that you usually do not have enough context for these attempts to be fruitful. Furthermore, if you are able to reproduce the problem in a test environment, that is only the first step, now you need to identify the root cause of the problem and resolve it!
So to summarize, APM is important to you so that you can understand the behavior of your application, detect problems before your users are impacted, and rapidly resolve those issues. In business terms, an APM solution is important because it reduces your Mean Time To Resolution (MTTR), which means that performance issues are resolved quicker and more efficiently so that the impact to your business bottom line is reduced.