The following is an excerpt from: An Introduction to Application Performance Management (APM).
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, let's consider the alternatives to adopting an APM solution and assess the impact in terms of resolution effort and elapsed downtime.
First let's consider how we detect problems. An APM solution alerts you to the abnormal application behavior, but if you don't have an APM solution then you have a few options:
■ Build synthetic transactions
■ Manual instrumentation
■ Wait for your users to call customer support!?
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 you're 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 don't think I need to go into details about why this is a bad idea!
Next let's 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:
■ Review runtime logs
■ Attempt to reproduce the problem in a development/test environment
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 one's 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.